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A Competitive Ratio for Quantifying Competition Between Intercrops
Abstract
A simple competitive ratio (CR) is proposed as a measure of intercrop competition, to indicate the number of times by which one component crop is more competitive than the other. Intercropping data show that this CR term could be useful in (i) comparing the competitive ability of different crops, (ii) measuring competitive changes within a given combination, (iii) identifying which plant characters are associated with competitive ability, and (iv) determining what competitive balance between components is most likely to give maximum yield advantages.
... LER is the land required with sole cropping to produce the yield obtained with intercropping with the same management (Willey, 1979). It is a commonly used approach to assess the land use advantage associated with intercropping (Willey and Rao, 1980): ...
... Legumes offer good prospects to increase yield in line with the principles of ecological intensification: legumes can improve soil fertility (Gbakatchetche et al.,2010), and provide crucial nutrients carry-overs for the subsequent cereal crop (Carsky et al., 2003). Intercropping of sorghum and cowpea could help adapt to climate variability: at any level of disaster, the intercrop system usually have a much lower probability of overall yield failure than either of the individual crops (Rao and Willey, 1980). Intercropping could therefore improve stability of productivity: its yield stabilizing effect residing in interspecies facilitation (Affolder et al., 2014) or compensation i.e., the two different crops are less likely to both be lost due to e.g., disease, pest or extreme climate (Raseduzzaman and Jensen, 2017). ...
... For historical and future climate, we computed the 31-year average calorie productivity (Ym), its standard deviation (stdY) and coefficient of variation (CV = stdY / Ym). The coefficient of variation is widely used to quantify and compare the stability or variability of productivity from year to year, with a greater CV value indicating higher yield variability, i.e. smaller yield stability and vice versa (Smith et al., 2007;Willey and Rao, 1980). ...
Dans la zone soudano sahélienne d'Afrique de l'Ouest, la productivité agricole est fortement affectée par la variabilité et les changements climatiques. La production agricole est dominée par la production pluviale de céréales telles que le maïs, le mil et le sorgho, pour la consommation alimentaire. Les agriculteurs ont des rendements faibles et variables, ce qui entraîne une incertitude croissante quant à leur capacité à produire davantage pour nourrir une population en forte croissance. L'objectif général de cette thèse était de concevoir des systèmes de culture plus productifs et stables, adaptés au changement climatique, en explorant les bénéfices de l'association sorgho-niébé, combiné a des choix contrastés de variété de sorgho, de fertilisation minérale et de date de semis. L'approche était basée sur un travail d'enquête, d'expérimentation au champ et de simulation à l'aide d'un modèle de culture, pour un cas d'étude au centre du Mali en Afrique de l'Ouest. Une première étape a porté sur l'identification de la perception du changement climatique par les agriculteurs et les stratégies d'adaptation agricole qu'ils considèrent pertinentes pour faire face à la variabilité et au changement climatique. En second lieu, le modèle de culture STICS a été calibré sur la base de deux années d'expérimentation (2017, 2018) de la culture associée sorgho-niébé à la station agronomique de N'Tarla. Dans ce dispositif expérimental, deux variétés de sorgho (locale et améliorée) avec une sensibilité contrastée à la photopériode ont été étudiées en culture pure et en culture associée avec le niébé. Deux dates de semis et deux niveaux de fertilisation minérale ont également été étudiés.
... The Land Equivalent Ratio (LER) was calculated using the equation proposed by Wiley and Rao (1980) [44]. It denotes the relative land area under a monocrop required to give the same yield as that obtained under a mixed or an intercropping system at the same level of management [45]. ...
... The coefficient (k) gives the yield per unit of area for calculating the 'expected' yields on the basis of how much of the area is initially allocated to each crop [44]. In this equation, kab is the relative crowding coefficient of Crop a intercropped with Crop b, Yab is the yield per unit area of Crop a intercropped with Crop b, Yaa is the yield per unit of area of pure Crop a, Zab is the proportion of the intercropped area initially allocated to Crop a and Zba is the proportion of intercropped area initially allocated to Crop b. ...
... The competitive ratio (CR) gives the yield per unit of area, calculating the 'expected' yields on the basis of how much of the area is initially allocated to each crop [44] (4). ...
The benefits of cereal-legume mixed cropping is a sustainable agricultural practice. However, knowledge of the genotypic differences of semi-leafless pea varieties is not enough to help them compete with cereals. In this study, the effects of Lithuania’s newest Pisum sativum cultivars (‘Egle DS’ and ‘Lina DS’) and, for comparison, a control cultivar (‘Jūra DS’) established with Avena sativa in mixed cropping system were investigated. Three years of field trials (2018, 2019 and 2020) with four experiments involved three different mixtures of each field pea cultivar with oat. The aboveground biomass of mixed cropped new field pea cultivars was found to be significantly higher: biomass of cultivars ‘Egle DS’ increased by 17.0% and ‘Lina DS’ by 7.2% on average compared with the control cultivar ‘Jūra DS’. For the mixed cropping system, statistically greater total aboveground biomass was observed with plant ratios of 50% pea + 50% oat and 60% pea + 40% oat compared to peas monocultures. Mixed cropped oat was the dominant species in all tested mixture compositions; however, the highest total grain yield of mixed crops was obtained when new pea ‘Lina DS’ and ‘Egle DS’ cultivars were included in the mixtures compared with the control cultivar. The new pea cultivar ‘Egle DS’ had a greater effect on protein content compared to other tested pea cultivars. In the new pea cultivars ‘Lina DS’ and ‘Egle DS’, the higher photosynthetic capacity and aboveground biomass of mixed cropped pea with oat showed mixture effects in the mixed cropped system and could increase total yield compared with pea monoculture. Generally, the new pea cultivars displayed a greater Land Equivalent Ratio (LER) value, resulting in the greatest yield among the mixtures on average for all three years and all four experiments. Future research could optimize the effects of pea cultivar mixtures with cereals to further improve the yield of organic mixed cropping systems.
... where YF and YO = Yield in kg ha -1 at corresponding fertilizer rates; Uf and UO = Uptake of nitrogen, phosphorus and potassium in kg ha-1 at corresponding fertilizer rates. The intra-and interspecific competition in the ricecowpea intercropping system was assessed using the land equivalent ratio-LER (Mead and Willey, 1980), the relative crowding coefficient-K (Willey and Rao, 1980) where, Kij and Kji = relative crowding coefficients of crop i intercropped with crop j and crop j intercropped with i; Yij and Yji = yields per unit area of i intercropped with j and j intercropped with i; Yii and Yjj = yields per unit area of sole crop i and sole crop j. The crop component that had a higher coefficient was said to be dominant. ...
... where YF and YO = Yield in kg ha -1 at corresponding fertilizer rates; Uf and UO = Uptake of nitrogen, phosphorus and potassium in kg ha-1 at corresponding fertilizer rates. The intra-and interspecific competition in the ricecowpea intercropping system was assessed using the land equivalent ratio-LER (Mead and Willey, 1980), the relative crowding coefficient-K (Willey and Rao, 1980) where, Kij and Kji = relative crowding coefficients of crop i intercropped with crop j and crop j intercropped with i; Yij and Yji = yields per unit area of i intercropped with j and j intercropped with i; Yii and Yjj = yields per unit area of sole crop i and sole crop j. The crop component that had a higher coefficient was said to be dominant. ...
... The crop component that had a higher coefficient was said to be dominant. If the coefficient of a particular crop species is less than, equal to or greater than 1, then that species has produced less yield, the same yield, or more than "expected", respectively ( (Willey and Rao, 1980). Aggressivity (Taha and El-Mahdy, 2014) is a measure of how much the relative yield in a species i is greater than that for species j. ...
... where YF and YO = Yield in kg ha -1 at corresponding fertilizer rates; Uf and UO = Uptake of nitrogen, phosphorus and potassium in kg ha-1 at corresponding fertilizer rates. The intra-and interspecific competition in the ricecowpea intercropping system was assessed using the land equivalent ratio-LER (Mead and Willey, 1980), the relative crowding coefficient-K (Willey and Rao, 1980) where, Kij and Kji = relative crowding coefficients of crop i intercropped with crop j and crop j intercropped with i; Yij and Yji = yields per unit area of i intercropped with j and j intercropped with i; Yii and Yjj = yields per unit area of sole crop i and sole crop j. The crop component that had a higher coefficient was said to be dominant. ...
... where YF and YO = Yield in kg ha -1 at corresponding fertilizer rates; Uf and UO = Uptake of nitrogen, phosphorus and potassium in kg ha-1 at corresponding fertilizer rates. The intra-and interspecific competition in the ricecowpea intercropping system was assessed using the land equivalent ratio-LER (Mead and Willey, 1980), the relative crowding coefficient-K (Willey and Rao, 1980) where, Kij and Kji = relative crowding coefficients of crop i intercropped with crop j and crop j intercropped with i; Yij and Yji = yields per unit area of i intercropped with j and j intercropped with i; Yii and Yjj = yields per unit area of sole crop i and sole crop j. The crop component that had a higher coefficient was said to be dominant. ...
... The crop component that had a higher coefficient was said to be dominant. If the coefficient of a particular crop species is less than, equal to or greater than 1, then that species has produced less yield, the same yield, or more than "expected", respectively ( (Willey and Rao, 1980). Aggressivity (Taha and El-Mahdy, 2014) is a measure of how much the relative yield in a species i is greater than that for species j. ...
... LER giving that all other things being break even with degree of the surrender advantage gotten by developing two or more crops or assortments as an intercrop compared to developing the same crops or assortments as a collection of partitioned monocultures [10]. Aggressivity is another list which speaks to a straightforward assessment of the relative abdicate increment in 'a' edit over 'b' trim in an intercropping framework, [11] proposed competition proportion (CR) rather than "aggressivity" to show the degree that one species competes with the other in an intercrop framework. The CR speaks to the proportion of person LERs of the two intercropped components and takes into consideration the extent of the crops in which they are at first planted. ...
... Intercropping advantage and competition between indiofera and brachiaria in intercrops were calculated agreeing to [11,13,14]. Land identical proportion (LER) was utilized to measure the effectiveness of the intercropping treatments. ...
... In the event that Aab=0, both crops are similarly competitive, in case Aab is positive, 'a' is overwhelming, while in the event that Aab is negative, 'b' is the prevailing trim. Willey RW, et al. [11] recommended competition proportion (CR) rather than "aggressivity" to show the degree that one species competes with the other in an intercrop framework. The CR speaks to the proportion of person LERs of the two intercropped components and takes into consideration the extent of the crops in which they are at first planted. ...
Blended societies can increment plant development and surrender through proficient utilize of assets. The reason of this consider was to decide the range comparable proportion of the secured crops leguminosae Indigofera zollingeriana (Iz) and the tropical grass Brachiaria humicola (Bh) in coconut ranches. The reason of this think about was to survey the arrive comparable proportion of this secured edit based on abdicate and bearing capacity on the coconut ranch. This test was performed employing a completely randomized plan with a combination of four medications of planted region as takes after: Iz planted range with 1.0 m x1.0 m and 1.0 m x1.5 m, and Bh planted zone with 0.5 m x 0.25 m, 0.5 m x 0.5 m. We analyzed the information utilizing ANOVA and HSD test. The factors measured were the potential surrender, carrying capacity and competition records based on dry matter surrender. The comes about appeared that the medicines contrasted essentially (P <0.01) with regard to the potential surrender, carrying capacity, land equivalent ratio and competition ratio. It can be concluded that Iz covered crops with a planted area of 1.0 m x 1.5 m and Bh with a planting area of 0.5 m x 0.25 m have the most appropriate yield and competitive indices.
... Competitive Ratio (CR) was proposed by Willey and Rao (1980) [13] . They suggested that instead of taking the difference of two terms of aggressivity, take the ratio of these terms which they designed as Competitive Ratio (CR). ...
... Competitive Ratio (CR) was proposed by Willey and Rao (1980) [13] . They suggested that instead of taking the difference of two terms of aggressivity, take the ratio of these terms which they designed as Competitive Ratio (CR). ...
A field experiment was carried out during the winter (rabi) of 2019-20 at Agronomy Instructional Farm, Chimanbhai Patel College of Agriculture, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar to study the effect of intercropping in mustard (Brassica juncea L.) nine treatment combination viz., T1: Sole mustard, T2: Sole chickpea, T3: Sole field pea, T4: Mustard + chickpea (1:2), T5: Mustard + chickpea (1:3), T6: Mustard + chickpea (1:4), T7: Mustard + field pea (1:2), T8: Mustard + field pea (1:3) and T9: Mustard + field pea (1:4) were laid out in randomized block design replicated 3 times. Among different intercropping systems, mustard + field pea (1:4) recorded maximum aggressively, crowding coefficient and competitive ratio in mustard. While, Area time efficiency ratio, production efficiency, system profitability, value: cost ratio and relative value total maximum observed in Mustard + chick pea (1:3) ratio.
... Land equivalent ratio (LER; Willey and Rao, 1980) was used to assess the land productivity of intercrops relative to monocrops: ...
... Competitive ratio (CR; Willey and Rao, 1980) was used to assess the competitiveness of one species compared to its companion species in an intercrop: ...
Combinability of species in intercrops depends on the production conditions and there is limited information on the potential of intercropping under conventional (i.e., non-organic) management in Western Europe. Here we determined productivity of four crop species (maize, Zea mays L.; wheat, Triticum aestivum L.; faba bean, Vicia faba L.; pea, Pisum sativum L.) in six different bi-specific mixture compositions. Species were spring-sown and fertilized in their strips according to common practice for monocrops. Strips were 1.5 m wide enabling strong interspecific interactions. Intercrops with maize, a species sown and harvested later than the other three species, had land equivalent ratio (LER) values that were in four out of six cases significantly greater than one, from 1.14 ± 0.04 to 1.22 ± 0.05 in 2018, and from 0.98 ± 0.06 to 1.15 ± 0.01 in 2019. Simultaneous intercrops comprising two of the other three species had LER values that tended to be lower than one, even though many LERs were not significantly different from one: from 0.94 ± 0.02 to 0.95 ± 0.04 in 2018, and from 0.80 ± 0.08 to 0.93 ± 0.04 in 2019. The yield gain (net intercropping effect; NE) in relay intercrops with maize ranged from 1.33 ± 0.59 to 2.01 ± 0.54 Mg ha⁻¹ in 2018, and from 0.29 ± 0.41 to 1.04 ± 0.14 Mg ha⁻¹ in 2019. The NE of simultaneous intercrops ranged from −0.43 ± 0.13 to −0.27 ± 0.22 Mg ha⁻¹ in 2018, and from −1.17 ± 0.49 to −0.36 ± 0.22 Mg ha⁻¹ in 2019. Results indicate that temporal complementarity between species drove the LER (or NE) in these experiments. On the other hand, values of the LER (or NE) were similar in species combinations with or without legumes, suggesting no major role for complementarity for nitrogen capture under the conditions of the study. Faba bean was the most competitive species and reached high partial LER and NE values in intercrops at the expense of the companion species. Competition from faba bean reduced the grain yield of wheat and pea more than it increased faba bean grain yield, resulting in negative net effects. Results suggest that relay strip intercropping can improve land use efficiency and total grain yield in conventional farming in Western Europe if species have temporal complementarity.
... (3) (6) To measure the competitive ability of intercrops, to identify the dominant partner producing relative higher proportion of biomass in the mixture than the other partner and to indicate the degree of dominance, a simple competitive ratio (CR) is considered. CR refers to the ratio of the PLERs of the two partners in the intercropping (Willey & Rao, 1980), and, by analogy, to the ratio of the PEERs. ...
... (Willey & Rao, 1980). PLER SW = Wheat mix /Wheat mono(1) PLER FB = Bean mix /Bean mono (2) LER = PLER SW + PLER FB(3)where Wheat mono and Bean mono are the biomass of SW and FB in monoculture and Wheat mix and Bean mix are the biomass of each crop in the mixture. ...
Aims. Intercropping cereals and grain legumes has the potential to increase grain yield in comparison to the respective sole crops, but little is known about mixture effects at the early crop developmental stage. In cereal legume mixtures, the cereal is usually the dominating partner. We aimed to find out when domination starts, which factors may enhance early domination, and if there is a legacy effect of early domination on later growth stages.
Methods. We set up field trials at a low input conventional site in 2020 and an organic site in 2020 and 2021. Treatments included all possible monocultures and 1:1 mixtures of twelve spring wheat (SW) entries, and two faba bean (FB) cultivars. All combinations were each sown in two sowing densities. To measure the effect of the mixture on early crop development, we counted crop emergence (plant m− 2) at ~ 23 days after sowing (DAS) and crop biomass dry matter at ~ 52 and ~ 82 DAS.
Results. We found positive mixture effects on SW emergence at the conventional site and on SW and FB emergence at the organic site in 2021. SW was the dominating partner in all three environments; SW domination, without suppressing FB, was already noticed at emergence at the conventional site. There, a small head start of SW at emergence favored dominance at later growth stages and lead to superiority over FB in terms of plant biomass.
Conclusions. Understanding early dominancy in intercropping may help in managing competition in mixture to enhance complementarity and improve total productivity.
... The competition index, the competition ratio (CR), and the aggressivity were calculated according to the method described by [29]. ...
... To assess the performance of the intercrop and the fertilizer microdosing in economic terms, two indices were calculated, namely the MAI (Monetary Advantage Index) according to [29] and the VCR (Value Competitive Ratio) according to [19,30,31]. ...
Climate change is affecting crop production in the West Africa Sahel. Farmers develop many adaptation strategies However, few of them have been tested to find their climate smartness, primarily their agronomic and economic benefits. Therefore, this study aimed to evaluate the field experiment in two successive years, 2020 and 2021, in rainy conditions, the combined effect of millet/cowpea intercropping and fertilizer microdosing on the yield and their economic advantages. Two genotypes of cowpea (ISV128 and Tiligré) and a variety of millet, Heini Kirey Précoce (HKP), were intercropped. At the treatment level, there is a net benefit of the crop association compared to the pure cultivation of each of the millet and cowpea species with total LERs, an average of 1.48 in 2020, and 1.43 in 2021 for microdose treatment and 1.55 in 2020 and 1.13 in 2021 for the control. However, there is no significant difference in cowpea genotype on LER and millet yields in the 2 years (P = 0.65 in 2020 and 0.29 in 2021). Yields of millet and cowpea were higher in the sole crop than in intercropping. The intercropping showed a significantly higher monetary advantage than the sole millet crop in both years. ISV128 is the most profitable because it is less competitive and less aggressive in intercropping with millet and offers a considerable monetary advantage. The findings are invaluable in implementing resilience strategies for smallholders who must be encouraged to adopt these cultural practices due to global warming.
... The land equivalent ratio (LER) was calculated following Eq. 9 (Willey and Rao 1980): where Y IM and Y SM mean maize yield in intercropping and sole cropping systems, respectively, and Y IP and Y SP mean peanut yield under intercropping and sole cropping systems, respectively. ...
... LER can be used to evaluate intercropping efficiency (Willey and Rao 1980). In most available studies on cereal-legume intercropping, such as soybean-millet intercropping (Jahanzad et al. 2015), alfalfa (Medicago sativa L.)-maize intercropping (Zhang et al. 2011a), and soybean-maize intercropping Undie et al. 2012), cereal-legume intercropping increases land-use efficiency and their LER are all greater than 1. ...
Aims
The objective of this study was to propose a maize–peanut intercropping system for traditional sole maize to increase economic benefits and decrease environmental pollution for dryland farming.
Methods
The treatments comprised sole maize, sole peanut, maize–peanut intercropping, maize–peanut intercropping–rotation (rotation of the maize and peanut planting strips every year), and maize–peanut intercropping–rotation with 20% and 40% N reduction in maize planting strip. Soil water and total N stock, photosynthetic traits, yield, greenhouse gas emissions, economic income, and interspecific relationships were evaluated.
Results
Intercropped maize absorbed more moisture but lost more N than sole maize. Maize–peanut intercropping had higher economic benefits and less N2O emissions than sole maize, but had no intercropped advantage on land equivalent ratio. In addition, intercropping increased the continuous cropping barriers of peanuts than a sole peanut. Rotation of the planting strips in intercropping increased the peanut yield and economic benefits compared with not rotating the planting strips, and the economic benefits reached the highest level in the third planting year. A 20% N reduction in maize planting strips can decrease the global warming potential without affecting economic benefits. A 40% N reduction in maize planting strips could reduce soil N stock, maize yield, water use efficiency, N use efficiency, land equivalent ratio, and income.
Conclusions
A maize–peanut intercropping–rotation system is recommended for dryland farming since it promoted efficient use of N and economic benefits and decreased N2O emission. The proper N reduction in maize planting does not lead to N stress but decreased global warming potential.
... In general, when the product of the two coefficients (K main crop x K intercrop) is greater than, equal to, or less than unity means that, the given crop is more, equal, or less competitive than its associated crop [15]. ...
... The Competitive ratio is an important index that determines the extent to which one crop competes with the other. It gives a better measure of the competitive ability of component crops in a polyculture and is a better index compared to relative crowding index (K) and aggressively (A) [15]. ...
Competition among component crops in an intercropping system is an important factor that influences productivity. To realize the benefit of intercropping in terms of higher productivity per unit area, the competitive behaviour of component crops needs to be quantified. As such, an experiment was conducted to determine the competitive behaviour of component crops in cassava-legume-based intercropping systems. The experiment was a factorial randomized complete design with three replications. The treatments consisted of seven cropping associations and two spatial arrangements. The result shows that both land equivalent ratio and area time equivalent ratio was greater than one and was higher for the cassava-soybean system compared to the other cropping systems. In general, the land equivalent ratio was higher than the area time equivalent ratio across the three agro-climatic zones. In the case for the competitive ratio and the relative crowding coefficient, both indices were higher for cassava compared to the legumes and were also higher for the cassava-soybean system compared to the other cropping systems. Also, both indices were on average higher when the legumes were intercropped with cassava using the 2 m x 0.5 m spatial arrangement. The result further shows a higher monetary advantage index for all cropping systems compared to monocropping. In conclusion, it was shown that, cassava-legume-based intercropping systems were advantageous in terms of both competitive and economic indices.
... a-Land equivalent ratio (LER)was determined according to the following formula described by Willey and Rao (1980): ...
... Competition ratio defined as a measure of intercrop competition to measure the number of times by which one component crop is more competitive than the other [41]. Despite, many indices to compare the interspecific competition in an intercropping system, none of them effectively define the competition effect of the component crops [42] as with CR. Thus, competition between component crops in this cropping system was measured by the competition ratio [43] using the following formula. ...
In Ethiopia the facts of farmer's indigenous knowledge based cropping system has been rarely investigated through research. A field experiment was conducted during 2021/2022 main cropping season at Fogera plain with the objective of examining the effect of additive series relay intercropping of grass pea with lowland rice on the grain yield of the component crops and production efficiency of the cropping system. The experiment consisted of a factorial combination of four seed proportion of grass pea (SPGP) (25%, 50%, 75% and 100% of the recommended seed rate of sole grass pea) relay intercropped with full seed rate of rice in four Rice: Grass pea spatial arrangements (SA) (1:1, 2:1, 3:1 and their mixed relay intercropping system). The treatments were arranged in Randomized Complete Block Design with three replications. Data on grain yield of the component crops were collected and analyzed using SAS-JMP-16 software. Results revealed that SPGP and SA had no significant effect on rice. The highest grain yield of grass pea was obtained when 25% SPGP was relay intercropped with rice in 1:3 SA (5.10 t ha-1). Maximum production efficiency in terms of total land output yield (9. 89 t ha-1) and land use efficiency (ATER =1.33), net benefit (33, 5176.79 Birr ha-1), marginal rate of return (21,428%) and positive monetary advantage index with lower competitive ratio was obtained when 50% SPGP was relay intercropped with rice in 1:3 SA. Thus, this mixture seems contributing in the development of sustainable crop production with a limited use of external inputs. Rice intercropping with other staple legume crops under residual soil moisture needs to be tested across locations and years to intensify the production efficiency and profitability of the cropping system.
... CR was used to assess the competitive ability of the component crops in an intercropping system. It was calculated using the following formula below [19]: ...
A field experiment was conducted at the teaching and research farm of the Faculty of Agronomy and Agricultural Sciences of the University of Dschang to investigate the effects of potato–Mucuna intercropping pattern on the agronomic performances of potatoes and the soil physicochemical properties in western highlands of Cameroon. The experiment design was a randomized complete block with three replications. The treatments included a pure potato stand (T1), pure Mucuna stand (T2), 1:1 (T3), 1:2 (T4), and 2:1 (T5) potato–Mucuna intercropping patterns. The results revealed that potato–Mucuna intercropping patterns had no significant effect (P > 0.05) on potato growth variables, soil physical properties, and the relative crowding coefficient. The highest potato yield (24,913 kg ha−1) and potato equivalent yield (81,513 kg ha−1) were obtained from the 1:1 intercropping pattern. The highest total LER (2.17) and the lowest (1.38) were obtained with 1:1 and 1:2 intercropping patterns, respectively. Area time equivalent ratio values were greater than 1 in 1:1 (1.46) and 2:1 (1.29) intercropping patterns. Mucuna proved to be the most aggressive and competitive species according to Ap and competitive ratio values except for the 1:2 intercropping pattern with K indicating a yield advantage in all intercropping patterns. 1:1 and 2:1 intercropping patterns gave the best C/N (13.94) and cation exchange capacity (36.12 meq 100 g−1), respectively. Late blight incidence was highest (16.88%) on potato sole crop stand and lowest (8.05%) on 1:2 intercropping pattern. Therefore, based on the findings of this experiment, 1:1 or 1:2 intercropping pattern could be recommended in potato–Mucuna intercropping system.
... The competition ratio was calculated using the formula proposed by Willey and Rao (1980 where: S a = relative space occupied by crop a S b = relative space occupied by crop b ...
Intercropping is the system of simultaneously growing two or more crops on the same field area with a definite row arrangement. However, it is critical to ensure that component crops do not compete for space, moisture, nutrients, or sun radiation with one another. Intercropping cereals and legumes increases the potential for reducing the negative effects of moisture and nutrient stress while also boosting system productivity and soil. The falling productivity of cereal-based farming systems can be countered by legumes. It's critical to find the optimum intercrops and determine adequate nitrogen (N) doses for cereal components in intercropping systems, taking into account the leguminous component's biological nitrogen fixation (BNF). There are many successful models whish widespread application leads for enhancing cereal-based cropping.
... The F variance test was used to compare the mean of two treatments. Different indices of intercropping were calculated to study economic viability and feasibility of the intercropping systems as suggested by Pal et al. (1985); Willey and Rao (1980); Padhi et al. (2010). ...
A field experiment was conducted at CCS HAU, Hisar in randomized block design with thirteen treatments and replicated thrice to evaluate the efficiency of maize based intercropping systems by taking green gram, urdbean, groundnut and okra in two different proportions (planting geometries). Intercropping of maize with different crops (groundnut, urdbean, okra, green gram) was observed more profitable in terms of Land equivalent ratio (LER) as compared to sole planting. Okra crop was found most suitable and compatible intercrop for intercropping in maize. In terms of planting geometries tested for intercropping, paired row planting of maize at 45:60 cm along with two rows of intercropping between two pairs was found more efficient and profitable as compared to 1:1 row pattern of maize +intercrop. Among all the intercropping treatments, paired row maize (45:60 cm)+ two rows of okra recorded higher LER (1.54) and maize equivalent yield (10324 kg/ha) which were 54.0 and 69.7 percent higher than sole maize crop, respectively. Maize seed yield was observed highest with green gram intercropping in both paired row planting and 1 : 1 planting geometry while, equivalent yield was observed maximum with okra based intercropping system in both planting geometry.
... The competitive ratio (CR) among various treatment combinations was estimated usingthe formula below (Willey and Rao, 1980): ...
Intercropping is a popular way to boost crop yield and profitability by maximizing the use of natural and agricultural resources. A study was carried out to establish crop arrangement for sweet gourd and cauliflower intercropping systems. The experiment was carried out during two consecutive years of 2019-20 and 2020-21 to identify the appropriate cauliflower population for intercropping with sweet gourd for increased production and profitability. Seven treatments viz. T1= Sole Sweet gourd (2 m × 2 m), T2=100% Sweet gourd + 3 rows cauliflower 37.5% (60 cm × 50 cm), T3=100% Sweet gourd + 3 rows cauliflower 23% (60 cm × 80 cm), T4=100% Sweet gourd + 4 rows cauliflower 50% (50 cm × 50 cm), T5=100% Sweet gourd + 4 rows cauliflower 31% (50 cm × 80 cm), T6=100% Sweet gourd + 5 rows cauliflower 31% (40 cm × 100 cm) and T7=Sole Cauliflower (50 cm × 50 cm). The maximum sweet gourd equivalent yield (SGEY) 34.83 t ha-1 was obtained from T4. The maximum gross return (Tk. 278640 ha-1), gross margin (Tk. 180384 ha-1), BCR (2.85) and LER (1.40) were also observed from T4 and the lowest in sole cauliflower (T7). The overall results revealed that among the intercrop combinations 100% Sweet gourd+4 rows cauliflower 50% (50 cm × 50 cm) (T4) followed by 100% Sweet gourd + 3 rows cauliflower 37.5% (60 cm × 50 cm) (T2) combinations could be profitable combinations for cauliflower with sweet gourd intercropping system. Bangladesh Agron. J. 2022, 25(1): 129-138
... The competitive ratio (CR) as described by Willey and Rao (1980) was determined using the formula: ...
A field experiment was conducted from August to November, during the 2012 and 2013 cropping seasons at the Research Farm, University of Agriculture, Makurdi, Nigeria, to identify the optimum plant density of okra and intercropping effects on yields of egusi melon-okra mixture and to assess the yield advantages of the intercropping system. The experiment was a 3x3 split plot arrangement of treatments, fitted in a randomized complete block design (RCBD), replicated four times. The intercropping (sole egusi melon, sole okra and egusi melon-okra mixture) constituted the main plots, while the population densities of okra (33,000, 40,000 and 50,000 plants ha ⁻¹ equivalent) into egusi melon were allocated to the subplots. Results of study showed that to maximize intercrop yield of okra in an egusi melon-okra intercrop, the optimal population density of okra is 33,000 plants ha ⁻¹ , while that of 40,000 plants ha ⁻¹ is optimal to maximize intercrop yield of egusi melon. Intercropping egusi melon and okra significantly (P≤0.05) reduced yields of egusi melon (37.5 % and 40.5 % respectively, in years 2012 and 2013) and that of okra (9.7 % and 16.9 % respectively, in years 2012 and 2013). The highest mean land equivalent ratio value of 1.57 and highest land equivalent coefficient values of 0.60 and 0.63 respectively, in years 2012 and 2013, were recorded for okra sown into egusi melon at the population density of 40,000 plants ha ⁻¹ . It is most advantageous having both crops in intercrop when okra is sown into egusi melon at the population density of 40,000 plants ha ⁻¹ . This should therefore be recommended for Makurdi location, Nigeria.
... Land Equivalent Ratio was computed as stated by Mead and Willey (1980). Competitive Ratio was computed as stated by Willey and Rao (1980) ...
Field experiments were conducted to assess the effect of time of introduction of maize and cropping pattern on two varieties of soybean in a soybean/maize intercrop in 2007 and 2008 seasons at the University of Agriculture Makurdi. Three periods of introduction of maize were evaluated: (i) planting at the same time with soybean;(ii) introduction of maize two weeks after planting soybean and (iii) introduction of maize four weeks after planting soybean. There were five cropping patterns viz: (i) soybean variety Samsoy-2 planted sole (ii) soybean variety TGX 1448-2E planted sole (iii) maize variety DMR-ESR-Y planted sole (iv) Samsoy -2 intercrop with maize and (v) TGX1448-2E intercrop with maize. The experiment was a split plot laid on complete randomized block design replicated three times. Results obtained revealed that there was no significant effect of time of introduction of maize on any soybean parameter observed. Yield and yield components of soybean indicated significant effect of cropping pattern (P<0.01) with number of pods per plant and grain yield. Grain yield and number of pods per plant decreased in intercrop with soybean variety Samsoy-2 having the highest number of pods per plant and grain yield. The result on maize indicated that maize planted sole was significantly (P<0.01) taller than intercropped maize, there was significant (P<0.01) effect of time of introduction of maize and cropping pattern on maize plant height, ear length, ear diameter, survival and barrenness percentage and grain yield. The Land Equivalent ratio (LER) values indicated that higher yield advantages were obtained from maize introduced two weeks after planting soybean and maize intercropped with soybean variety Samsoy-2 (1.35) than with soybean variety TGX1448-2E (1.12).
... Fisher's Least Significant Difference (FLSD) was used for means separation at the probability level of 5% whenever differences between treatment means were significant. Land Equivalent Ratio (LER) as described by Ofori and Stern (1987), Competitive Ratio (CR) as proposed by Willey and Rao (1980) and percentage (%) land saved as described by Willey (1985) were used to determine the productivity of the intercropping systems. ...
Field trials were conducted during 2011 and 2012 cropping seasons at the Teaching and Research Farm of the University of Agriculture Makurdi, Benue State located in Southern Guinea Savanna of Nigeria. The objective of the study was to evaluate the response of some improved sweet potato varieties planted at three densities to intercropping with soybean. The experiment was a 2x3x3 split-split plot laid out in a randomized complete block design with three replications. The main plot consisted of two cropping systems [sole cropping (sweet potato, soybean) and intercropping (sweet potato + soybean). The sub-plot consisted of three sweet potato varieties (CIP440037, NRSP/05/007C and CIP440141). The sub-sub-plot treatment comprised of three sweet potato planting densities (25,000 plants/ha, 33,000 plants/ha and 50,000 plants/ha). Intercropping severely depressed the yields of both sweet potato varieties and the soybean component, such that intercrop yields were rarely above 50% of sole crop yields, irrespective of the sweet potato variety used. The number and weight of the sweet potato component was not significantly affected at the planting density of 50,000 plants/ha. Indices used to measure intercrop advantage showed that intercropping these sweet potato varieties with soybean was biologically efficient and percentage land saved varied from 23.08 and 32.43. Soybean was more competitive than sweet potato at all densities tested.
... The competitive ratio (CR) as described by Willey and Rao (1980) was determined using the formula: ...
A field experiment was conducted from August to November, during the 2012 and 2013 cropping seasons at the Research Farm, University of Agriculture, Makurdi, Nigeria, to evaluate the yield effects of egusi melon-okra intercrop as influenced by the interaction of time of introducing okra x cropping systems, and to assess the yield advantages of the intercropping system. The experiment was a 3x3 split plot arrangement of treatments, fitted in a randomized complete block design (RCBD), replicated four times. The cropping systems (sole egusi melon, sole okra and egusi melon-okra mixture) constituted the main plots, while the time of introducing okra (mid August, late August and early September) into egusi melon were allocated to the subplots. Results of study showed that to obtain optimal intercrop yield of okra in an egusi melon-okra intercrop, it is appropriate planting okra at the same time with egusi melon in mid August, while introducing okra into egusi melon in late August is appropriate to obtain optimal intercrop yield of egusi melon. Intercropping egusi melon and okra significantly (P≤0.05) reduced yields of egusi melon (37.5 % and 40.5 % respectively, in years 2012 and 2013) and that of okra (9.7 % and 16.9 % respectively, in years 2012 and 2013). The highest mean land equivalent ratio value of 1.57 and highest land equivalent coefficient values of 0.53 and 0.70 were respectively recorded, in years 2012 and 2013, for okra introduced into egusi melon in early September. These recommendations are appropriate for Makurdi location, Nigeria
... The CR is a more desired indicator of a crop's competitive capacity, and it is more beneficial as an index than the RCC and aggressivity (Willey & Rao, 1980). Intercropped Brahmi had a higher CR in DSR + Brahmi intercropping system indicating that Brahmi is more competitive than DSR. ...
Weed menace is the major biotic constraint in direct-seeded rice (DSR) cultivation as they cause higher yield loss. Hence, exploring different weed management options along with intercropping could be promising practice for improving crop productivity. Keeping this in view, an experiment was conducted at Pantnagar, Uttarakhand, India in 2015 and 2016 to evaluate the effect of different weed management practices in the DSR + Brahmi intercropping system for providing farmers with a practical and economically viable weed control solution. Two intercropping ratios along with four weed management practices in sole rice and sole Brahmi as control were evaluated. The results revealed the significant effect of weed management and intercropping on weed control efficiency (WCE) and different competition indices. The highest WCE (73.3 and 83.3%) was recorded with pendimethalin (pre-emergence) + cyhalofop-butyl (post-emergence) + 1 HW (hand weeding) at 45 DAS (days after sowing) in 2:1 ratio treatment. Similarly, significantly minimum density and weed biomass were also recorded under the same treatment. However, significantly higher values of relative yield total, aggressivity, relative crowding coefficient, and competition ratio were recorded in a 1:1 ratio of DSR + Brahmi. In conclusion, using Brahmi as an intercrop with DSR can help with weed management, reduces the use of pesticides, and increases profitability.
... Aggressivity (A) is an index that has been proposed to measure the strength of competition (Willey and Rao 1980). RY can be used to determine the agressivity index (McGilchrist and Trenbath 1971;Roush and Radosevich 1985). ...
ABSTRACT
Invasive species tend to pose a threat to ecosystem biodiversity, functioning, and ecosystem service provision. This study was conducted in Burkina Faso to assess the competitiveness of an invasive species Senna obtusifolia that is a less palatable legume plant in West African Sahelian rangelands. To address the research hypothesis that the recurrent drought in the Sahel results in S. obtusifolia being more competitive in the land invasion, we conducted an interspecific competition involving S. obtusifolia and 3 herbaceous species (Andropogon gayanus, Chamaecrista mimosoides, and Pennisetum pedicellatum) in a greenhouse experiment under four water stress regimes using a replacement series design. The height and biomass of each species were measured throughout four months experiment. In the severe water regime, S. obtusifolia was the most sensitive to water deficit while the 3 other species were found to be resistant. In addition, in all water regimes, the aggressivity index revealed that S. obtusifolia was less competitive than the grass species A. gayanus and P. pedicellatum. Further, the study discovered that drought in the Sahel made S. obtusifolia more vulnerable than the other species. Hence the invasion of Sahelian rangelands by S. obtusifolia could be favored by overgrazing that reduces fodder species' dominance and competitiveness. Good management of sahelian rangelands by controlling grazing could help to reduce S. obtusifolia invasion and provide more fodder for livestock.
... Competitive ratio (CR) of N, P, and K was employed to assess the competition intensity between tea plants and soybeans [31,32]. It is calculated as follows: ...
The positive aspects of the tea plant/legume intercropping system draw attention to the Chinese tea industry for its benefit for soil fertility improvement with low fertilizer input. However, limited information exists as to the roles of intercropped legumes in the rhizosphere microbiome and tea quality. Hereby, soybean was selected as the intercropped plant to investigate its effect on bacterial communities, nutrient competition, tea plant development, and tea quality. Our data showed that intercropped soybean boosted the uptake of nitrogen in tea plants and enhanced the growth of young tea shoots. Nutrient competition for phosphorus and potassium in soil existed between soybeans and tea plants. Moreover, tea/soybean intercropping improved tea quality, manifested by a significantly increased content of non-ester type catechins (C, EGC, EC), total catechins and theanine, and decreased content of ester type catechins (EGCG). Significant differences in rhizobacterial composition were also observed under different systems. At the genus level, the relative abundance of beneficial bacteria, such as Bradyrhizobium, Saccharimonadales and Mycobacterium, was significantly increased with the intercropping system, while the relative abundance of denitrifying bacteria, Pseudogulbenkiania, was markedly decreased. Correlation analysis showed that Pseudogulbenkiania, SBR1031, and Burkholderiaceae clustered together showing a similar correlation with soil physicochemical and tea quality characteristics; however, other differential bacteria showed the opposite pattern. In conclusion, tea/soybean intercropping improves tea quality and nutrition uptake by increasing the relative abundance of beneficial rhizosphere bacteria and decreasing denitrifying bacteria. This study strengthens our understanding of how intercropping system regulate the soil bacterial community to maintain the health of soils in tea plantations and provides the basis for replacing chemical fertilizers and improving the ecosystem in tea plantations.
... The competitive ratio (CR) was used to assess the competitive ability of the component crops in an intercropping system. The CR represents simply the ratio of the individual LERs of the two component crops [35,42]: ...
Cereals–soybean intercropping is not well studied, despite the importance of these crops in increasing agricultural profitability and ensuring nutritional and food security in Southeast Asia. We compared different intercropping practices (IPs) with monocropping practices (MPs) for their yield and economic performance by small-scale farms without mechanization. The treatments were IPs of rice–maize, rice–soybean, or maize–soybean compared with MPs of rice, maize, or soybean as sole crops, across three provinces in the rainfed areas of western Indonesia with a wet climate. Our results show that the yield advantages using the land equivalent ratio of the IPs were 44% for rice–maize, 54% for rice–soybean, and 63% for maize–soybean compared to MPs. Rice equivalent yield, maize equivalent yield, and the gross margin under IPs were significantly higher per cycle than under MPs; IPs provided a substantially lower cost of production and of paid workers. Compared to just rice, there were additional net return gains of USD 160 and USD 203 ha−1 per cycle under rice–maize and rice–soybean intercropping. Maize–soybean intercropping resulted in an additional net return gain of USD 153 ha−1 compared to just maize. These results suggest there is considerable potential for small farmers to increase their yields and profits by intercropping in rainfed areas with a wet climate.
... Competitive ratio (CR) is an important index to assess competition between species grown in intercropping. CR differs from aggressivity because it considers individual LERs and the proportion of the mix in the intercropping (Willey and Rao, 1980). The CR (Eqs. ...
Intercropping is a labor-intensive practice largely adopted by smallholder farmers to increase yield per unit area, cope with crop failures and market fluctuations, meet food preferences and increase farm income. A field experiment was conducted to examine the yield performances and intercropping efficiencies of sweet corn and okra planted in a young rubber plantation. The treatments were arranged in Randomized Complete Block Design (RCBD) with three replications. The treatments ratios were 20% okra + 80% sweet corn (strip and strip relay intercropping) with sole okra and sweet corn as the control. This consists of strips intercropping (okra and sweet corn planted on the same date), strip relay intercropping (sweet corn planted 4 weeks after okra planting), sole okra and sole sweet corn. The highest yield of okra was obtained from strip relay intercropping while the highest yield of sweet corn was produced from the pattern of strip intercropping. However, the economic analysis showed that the strip intercropping recorded the maximum gross margin and costbenefit ratio of RM 17,733.20 ha-1 and 2.09, respectively. Immature rubber growth was unaffected by intercropping with sweet corn and okra crops. Strip intercropping not only resulted in the higher land equivalent ratio (1.29), but also area time equivalent ratio, % land saved and monetary advantage index of 1.14, 22.28% and RM 7,583.50 ha-1, respectively compared with strip relay intercropping. The highest assessment of intercropping based on relative crowding coefficient was recorded by strip intercropping with 4.56. With regard to competition between the intercrops, okra was a more dominant species as measured by the positive value of aggressivity. However, strip intercropping was indicated the lowest competitive ratio than the strip relay intercropping. Thus, this intercropping pattern could be recommended to the farmers for adoption.
... Land equivalent ratio (LER), defined as the relative area of pure crops that would be required to produce the yields obtained by intercropping (IRRI, 1974). Competitive ratio (CR), the ratio of the individuals LERs of the two component crops after correcting for the proportions in which the crops where sown initially, were calculated as proposed by Willey and Rao (1980). The CR value gives the exact degree of competition by indicating the number of times one crop is more competitive than the other. ...
... Then, the parameters of plant height (in cm), stem diameter (in cm), head diameter (in cm), 100-seed weight (in g), seed yield (in g/plant), and seed yield (in kg/fed) were noted. According to A.O.A.C. (2007), seed oil percentage (%) was calculated using the Soxhlet apparatus Seed yield per feed and seed oil % were multiplied to determine oil yield (kg/fed). 3. Competitive relationships: a-Land equivalent ratio (LER) was determined according to the following formula described by Willey and Rao (1980): c-Relative crowding coefficient (RCC) or K was calculated according to De-Wit (1960) as follows: ...
... The competition indices evaluated in the intercropped systems from the tested cultivar combinations were as follows: competitive ratio (CR) and crop aggressivity indices (A). The CR was obtained with the formula suggested by Willey & Rao (1980) ...
This work aimed to evaluate the dynamics of agro-economic efficiency in combinations of vegetable cowpea and radish cultivars in strip-intercropping systems through agronomic, economic and competition indices tested by the Hsu test in a semi-arid environment. The experimental design was a completely randomised block with eight treatments and four replications. The treatments consisted of combinations of four cowpea cultivars, BRS Tumucumaque, BRS Cauamé, BRS Guariba, and BRS Itaim, with two radish cultivars, Crimson Gigante and Zapp. In each block, individual plots of these cultivars in single cultivation were planted as additional treatments to obtain the system indices. The indices of agronomic and economic efficiency and of competition evaluated were land equivalent ratio (LER), actual yield loss (AYL), land use efficiency (LUE%), score of the canonical variable (Z), gross income (GI), net income (NI), rate of return (RR), corrected monetary advantage (CMA), competitive ratio (CR) and the aggressivity of radish over cowpea (Ar) and cowpea over radish (Avc). The cowpea cultivar BRS Tumucumaque, when combined with the radish cultivar Zapp, provided the highest agro-economic efficiency of the intercropped system in a semi-arid environment. The complementarity and sustainability of the intercropping systems of cowpea and radish were observed in the results of the Hsu test applied to the indices of agro-economic efficiency and of competition. Radish was the dominant crop.
... It is an index used to measure the competition effect in intercropping. Willey and Rao, (1980) suggested that competitive ratio used to measure of better competitiveness of the crops over relative crowding coefficient and aggressivity. Competitive ratio can be calculated by using the following formula. ...
... 2-Land Equivalent Coefficient (LEC) is a measure of interaction concerned with the strength of relationship (Adetiloye et al., 1983) where a yield advantage is obtained if LEC value exceeds 0.2. 3-Competitive ratio (CR) was used to evaluate which one crop competes with the other in an intercropping system (Willey and Rao, 1980;Wahla et al., 2009). ...
A field experiment was conducted during two seasons in North Sinai, to study the effects of intercropping and density treatments on yield and the productivity of faba bean and onion plants. Combinations of intercropping and density treatments were used. The experimental design used in this study was RCBD with three replicates in five treatments: single faba beans, and single onions, as well as the three intermodal patterns (faba beans: onions) with the substitution method due to changed density ratios. Three intercropping patterns include different areas of faba bean and onions. The intercropping area ratios occupied by faba bean and onion were 11.8:88.2%, 7.6:92.4% and 4.9:95.1%, respectively, for the three respective manners. Intercropping effects were significant for yields of each crop species. On average, monoculture faba bean yielded 1.965 and 0.462 ton/fed seed dry and straw yields, respectively, as well as a sole onion of 15.95 ton/fed bulb yield. The mean faba bean seeds dry yield and, straw decreased by 17.2% and 3.4%, respectively while, bulbs yield increased by 82.6% when the faba bean plants densities/m 2 , in the intercrop, decreased from 4.0 to 2.9 plants/m 2 while increasing the onion plants rate/m 2 from 30 to 50 plants/m 2. The highest total intercrop yield of 15.125 ton/fed and a gross monetary value of 12853 L.E. was obtained when onion intercropped with faba bean in an intercropping pattern of F 3 O 3 (including 50 and 2.9 plants/m 2 for onion and faba bean, respectively). The gross monetary value followed the same trend as the total land equivalent ratio.
... (1) Land equivalent ratio (LER): It was calculated according to Willey and Rao (1980): ...
... 2-Land Equivalent Coefficient (LEC) is a measure of interaction concerned with the strength of relationship (Adetiloye et al., 1983) where a yield advantage is obtained if LEC value exceeds 0.2. 3-Competitive ratio (CR) was used to evaluate which one crop competes with the other in an intercropping system (Willey and Rao, 1980;Wahla et al., 2009). ...
... Further, the Excel software (Microsoft Office Home and Student version 2019-en-us, Microsoft Inc., Redmond, Washington, USA) was used for statistical analysis. Further, some competitive functions such as land equivalent ratio (LER), area time equivalent ratio (ATER), relative crowding coefficient (RCC) and competitive ratio (CR) were computed using the formula given by Willey and Osiru (1972), Hiebsch (1978), De Wit (1960 and Willey and Rao (1980). ...
Maize (Zea mays L.), the queen of cereals, has versatile use as food, feed and industrial purpose and the area under maize is increasing during recent times. As a widely spaced crop, it offers inclusion of intercrops without reducing the optimum plant stand. Intercropping legumes in maize is widely practiced to herness the efficient use of resource and multiple advantages. Based on the above facts, an experiment was conducted during summer season of 2021 on intercropping maize with legumes at Exp e rime ntal Farm of Ce nturion Unive rs ity of Te chnology and Manage me nt, Parlakhamundi, Odisha. The experiment was carried out in Randomized Block Design (RBD) comprising of nine treatments namely, T 1 : Maize sole, T 2 : Cowpea sole, T 3 : Cluster bean sole, T 4 : Maize + Cowpea (2:1), T 5 : Maize + Cowpea (2:2), T 6 : Maize + Cowpea (2:3), T 7 : Maize + Cluster bean (2:1), T 8 : Maize + Cluster bean (2:2) and T 9 : Maize + Cluster bean (2:3). The results revealed that the yield attributes of maize such as number of cobs/plant, number of rows/cob, number of seeds/row, test weight and cob length and maize yield were not significantly influenced among the treatments. In case of Land Equivalent Ratio (LER), the values obtained in all the intercropped treatments were greater than unity which clearly showed that intercropping was advantageous. However, the maximum LER and Area Time Equivalent Ratio (ATER) were obtained from 2:3 row proportion of maize + cluster bean and it was followed by maize + cowpea in 2:3 row ratio. Product of Relative Crowding Coefficient (RCC) was found maximum in the case of maize + cowpea (2:3). The competitive ratio depicts that those legumes were more competitive over maize. The study indicated that intercropping 2:3 row proportion of maize + vegetable legumes were advantageous over pure stand of maize.
... LER is the land required with sole cropping to produce the yield obtained with intercropping with the same management (Willey, 1979). It is a commonly used approach to assess the land use advantage associated with intercropping (Willey and Rao, 1980): ...
Intercropping is a key entry point for sustainable intensification of cropping systems in sub-Saharan Africa where variable rainfall conditions prevail. Crop simulation models can complement field experiments to assess the agronomic and environmental performances of intercropping systems under diverse climatic conditions, including hypothetical future climate. So far, crop models that can handle intercropping, such as STICS, have not often been extensively evaluated for tropical conditions and for species grown by farmers in sub-Saharan Africa. The objective of this study was to evaluate the performance of the calibrated STICS model to simulate sorghum-cowpea intercropping systems in rainfed conditions in West Africa. We used data from field experiments conducted at the N'Tarla Agronomic Station in Mali in 2017 and 2018. Two varieties of sorghum (local and improved) with contrasting photoperiod sensitivities were grown as sole crop and intercropped with cowpea, with additive design. Two sowing dates and two levels of mineral fertilization were also investigated. Model simulations were evaluated with observed data for phenology, leaf area index (LAI), aboveground biomass, grain yield and in-season soil moisture. Large variations in aboveground biomass of sorghum and cowpea was observed in the experiment (i.e. 3.5 – 9.6 t/ha for sorghum and 0.4–2.5 t/ha for cowpea), owing to the treatments (i.e. sole vs intercrop, early vs late sowing, no fertilizer input vs fertilizer input). Such variations were satisfactorily reproduced by the model, with EF of 0.81 in calibration and 0.58 in evaluation (with relative rRMSE of 23 % and 43 %) across crops. Sorghum AGB simulations were more accurate (rRMSE of 21 % and EF of 0.54) than cowpea AGB simulations (rRMSE of 25 % and EF of −0.09). The two main observed features of the intercropping system were well reproduced by the model. Firstly, cowpea and sorghum aboveground biomass decreased with intercropping compared with sole cropping, and the decrease in cowpea biomass was greater than the decrease in sorghum biomass. Secondly, despite a reduction in sorghum and cowpea yield, Land Equivalent Ratio of the intercropping for aboveground biomass was always above one. With regard to grain yield, observed LER was above one only in the non-fertilized treatment. The model failed at reproducing this behavior, probably because of insufficiently accurate calibration of the process leading to grain yield formation: rRMSE for grain yield was 49 % in calibration and 41 % in evaluation. Based on these findings, we discuss avenues to improve model calibration and use the model to explore options for sustainable intensification in land constrained sub-Saharan Africa.
... Several researchers have developed different concepts/indices while trying to evaluate the productivity and efficiency of different intercropping systems. Such indices include relative crowding effect, RCE (De Wit, 1960), crop equivalent factor, CEF (Donald, 1963), coefficient of agressivity, CA (Mc Gilchrist and Trenbath, 1971), land equivalent ratio, LER (Willey, 1979), competitive ratio, CR (Willey and Rao, 1980), land equivalent coefficient, LEC (Adetiloye et al., 1983), staple land equivalent ratio, SLER (Reddy and Chetty, 1984), area time equivalent ratio, ATER (Hiebsch and Mc Collum, 1987) and monetary equivalent ratio, MER (Adetiloye and Adekunle, 1989). These indices measure the productivity of the systems by comparing yields or monetary returns in intercropping with that of sole crop. ...
... Competitive ratio (CR) was calculated to measure the degree with which one crop competes with the other using the formula of [33]: CR (sesame) = Ls x Zsm/Lm x Zms CR (maize) = Lm x Zms/Ls x Zsm ...
... It's another indicator to detect how competitive various species. The competitive ratio (CR) is a preferable indicator of a crop's competitive aptitude, and it may also be utilized to compare aggressivity (Willey and Rao, 1980). The competitive ratio marks the percentage of the two plants in which they are primarily seeded by calculating the ratio of relative yield of every crop. ...
... The competitive ratio (CR) measures the degree of competition of one plant over another in an intercropping system and was used to assess possible competition of stylo over maize (CRs/m) in the MSI treatments using the following formula (Wahla et al., 2009;Willey and Rao, 1980): ...
La dégradation des terres liée à l'intensification agricole, principalement due à la baisse de la fertilité des sols et à l’érosion, est devenue une problématique majeure en Nouvelle-Calédonie. Le contexte insulaire et les spécificités pédoclimatiques rendent en outre les enjeux d’autosuffisance alimentaire, de préservation des agroécosystèmes et de la biodiversité, d’autant plus prégnants. Les systèmes de culture (sdc) doivent donc évoluer en mobilisant les processus biologiques afin d’être viables, performants et durables. L’agriculture de conservation (AC) consiste en un ensemble de pratiques culturales basé sur trois principes : une réduction, voire une suppression du travail du sol, une couverture végétale du sol permanente et une diversification des espèces cultivées. L’AC peut répondre à ces problématiques en alliant durabilité et productivité, et en favorisant un certain nombre de services écosystémiques. A travers une démarche originale intégrant approches fonctionnelle et systémique, cette thèse vise à quantifier les relations entre pratiques, fonctions et services écosystémiques au sein de sdc complexes. Dans le contexte spécifique de la côte ouest de la Nouvelle-Calédonie, afin de savoir si l’AC pourrait maximiser la fourniture de services écosystémiques, trois questions sont apparues importantes à aborder : quels sont les impacts des pratiques de l’AC sur la santé du sol et les performances agronomiques de sdc ?, quels sont les effets de l’AC sur la biodiversité fonctionnelle (macrofaune) ?, et quelles sont les performances et l’efficience d’utilisation des ressources de sdc en AC notamment sous couvert végétal vivant ? Afin de répondre aux deux premières questions, une expérimentation système, initiée en 2011, a permis de comparer en 2018 trois sdc en production de maïs : un sdc en monoculture et en labour, représentant la pratique de référence de la région (CT), un sdc en AC sous couvert végétal mort (mélange de 4 espèces annuelles) (CA-DM), et un sdc en AC sous couvert végétal vivant (Stylosanthes guianensis) (CA-LM). Une expérimentation analytique a également été mise en place en 2018 afin d’évaluer les performances et l’efficience d’utilisation des ressources d’une association maïs-Stylosanthes guianensis en AC sous couvert végétal vivant. D’une part, l’impact du mode de conduite de ces trois sdc sur la santé du sol a été caractérisé via l’utilisation de Biofunctool®. Biofunctool® est une méthode d’évaluation fonctionnelle de la santé des sols basée sur une approche intégrative prenant en compte les liens entre les propriétés physico-chimiques et l'activité biologique des sols. Elle permet de mener une analyse des fonctions principales du sol : i) la transformation du carbone, ii) le recyclage des nutriments, et iii) le maintien de la structure du sol. D’autre part, un outil fonctionnel (SMS) est proposé afin de mesurer l’impact de pratiques culturales sur l’activité de la macrofaune du sol. Il permet d’intégrer trois fonctions de la macrofaune : i) la dégradation de la matière organique, ii) l’ingénierie de l’écosystème, et iii) la régulation des ravageurs. Enfin, l’évaluation de l’efficience d’utilisation des ressources (i.e., eau, azote, lumière, surface) et des performances de ces sdc contrastés a été menée à l’aide de la modélisation par équations structurelles.
... The land equivalent ratio was calculated for both introduction times using the equation proposed by Willey and Rao [10]. ...
Background and Objective: The time of sowing component crops is an important management variable that can improve productivity and increase land equivalent ratio in intercropping systems. The study aimed to evaluate the effect of the time of introduction of legumes into cassava on cassava productivity. Study Design: The experiment was a factorial randomized complete block design with three replications. Place and Duration of Study: Field trials were conducted in 2015/2016 and 2016/2017 cropping seasons in three agro-climatic zones.
Intercropping has been a globally accepted practice for forage production, however, consideration of multiple performance criteria for intercropping including forage production, feed use efficiency and ruminal greenhouse gas emissions needs to be further investigated. A two‐year field study was conducted to evaluate forage dry matter (DM) yield, nutritive value, feeding values and land‐use efficiency as well as ruminal carbon dioxide (CO2) and methane (CH4) emissions of intercropped orchardgrass (Dactylis glomerata) and alfalfa (Medicago sativa) sown in five intercropping ratios (100:0, 75:25, 50:50, 25:75, and 0:100, based on seed weight) and three nitrogen (N) fertilizer levels (0, 50, and 100 kg ha−1). Increasing alfalfa proportion and N fertilizer level increased soil nutrients and the two‐year total DM yield. Intercropping increased both land and nitrogen use efficiency (NUE) compared with monocultures. Greater NUE was obtained when N fertilizer was applied at 50 kg ha−1, compared with 100 kg ha−1. Increasing the proportion of alfalfa in intercrops increased the crude protein yield and rumen undegraded protein yield. Harvested forage intercrops were incubated with ruminal fluid for 48 h. Degraded DM yield, CO2 and CH4 emissions increased with increasing alfalfa proportion in intercrops. Overall, the 75:25 of orchardgrass‐alfalfa intercrops was recommended as the best compromise between high forage productivity, superior feed use efficiency and low ruminal greenhouse gas emissions through complementary effects. The results indicate that the appropriate N fertilization level would be 50 kg ha−1 for acquiring higher nitrogen use efficiency and forage productivity.
In dryland farming, maize (Zea mays L.) and peanut (Arachis hypogaea L.) intercropping has been widely practiced to achieve sustainable agriculture goals. However, only a few studies have investigated the effect of reducing nitrogen (N) application on the performance of maize and peanut crops in intercropping system based on rotation of the planting strip. Therefore, a field study was conducted from 2018 to 2020 in Yangling, China, where the treatments comprised peanut monoculture, maize monoculture, maize–peanut intercropping, maize–peanut rotational intercropping, and maize N reduction based on the rotational intercropping system. The N accumulation and yield in maize increased after intercropping, while the N accumulation, yield and N fixation capacity of peanut decreased than other treatments. In addition, soil residual N, ammonia volatilization, N leaching, and N2O emissions of maize–peanut intercropping significantly decreased than maize monoculture. The rotation of planting strips in maize–peanut intercropping had increased the land equivalent ratio by 3.06 % and 9.39 % and N recovery efficiency by 15.45 % and 27.37 % in the second and third years of planting, as well as alleviated the continuous cropping barrier for peanuts. N reduction does not affect N fixation capacity and yield of peanut and reduces ammonia volatilization and N leaching from farmland, although it does influence maize yield. The optimal cropping system was a 20 % N reduction in maize planting strip under rotational intercropping because N accumulation and the farmland productivity were not affected significantly, while the N losses to the environment also decreased by an average of 44.17 % and 14.87 % compared with traditional intercropping and monoculture in the second and third years of planting. These results are useful for optimizing cropping systems to promote sustainable development in dryland regions and mitigate N pollution.
A proposal for determining the in situ conservation unit size in home gardens: The case
of chayote (Sechium edule L.) in Guatemala. Huisquil or chayote (Sechium edule) is a cucurbit crop native to Mexico and Guatemala, where wild chayote and its wild relative species (S. compositum) thrive. Chayote in Guatemala is primarily cultivated in home gardens everywhere it occurs, suggesting that its germplasm is best conserved in such ecosystem. Two areas with contrasting cultural and ecological conditions were studied in Alta Verapaz province in the north of the country. The goal of the study was to determine the intra-specific genetic variability in order to have basic knowledge for determining the in situ conservation unit. In situ morphological characterization showed differences in qualitative and quantitative fruit traits. Biochemical characterization using isozymes indicted differences in both allelic frequencies and gene heterozygosity. AFLPs analysis showed that S. compositum and wild S. edule are closely related to each other and widely isolated from Guatemalan cultivated varieties. There was not a noticeable separation between materials from the two eco-regions. As a general statement, one can say
that the results showed differences within home gardens and localities, and also to some degree at the eco-region level. To define how many and which localities would be selected to make up an in situ conservation unit, a methodology for identifying the localities that harbor the highest genetic diversity is suggested. It is based on the cluster analysis generated by using morphological, biochemical and molecular traits.
Key words: Chayote, genetic diversity, home gardens, in situ conservation
Sugarcane offers a unique potential for intercropping. To ensure the optimum productivity in an intercropping system, one must ensure that the peak periods of growth of the two crops do not coincide, so that one quick-maturing crop completes its life cycle before the main period of growth of the other crop starts. Though economic efficiency of sugarcane (Saccharumofficinarum) intercropping system has attracted a lot of attention around the world, interspecific competition between sugarcane and intercrops has not been studied so far. Field experiments were conducted during 2014–2015 and 2015–2016 at ICAR—Sugarcane Breeding Institute in split plot design with three rates of Nitrogen (N) (100, 75 and 50% of recommended N) to sugarcane as main plot treatments and six intercrops (I), namely finger millet, black gram, soybean, sesame, amaranthus and sunn hemp along with sole crop of sugarcane as subplot treatments. The yield and nitrogen balance of sugarcane and intercrops, and quality of sugarcane juice were determined. Land equivalent ratio (LER), was used to evaluate the potential advantages of the intercrops, Area Time Equivalency Ratio (ATER), Aggressivity (AG), and competitive ratio (CR) which based on crop yield and nitrogen acquisition were used to evaluate interspecific competition between sugarcane and intercrops. The results indicated that sugarcane–intercropping system had intercropping advantages based on LER. Application of 100% N has recorded higher number of millable canes and cane yield compared to 75% and 50% N levels. However, the cane yield at 100% N was on par with 75% N during 2015–2016. Higher ATER and CR recorded in case of sugarcane + soybean. Aggressivity (AG) was higher at 100% N level indicates its optimal dosage of N for the sugarcane growth. AG is greater than zero, indicating the competitive ability of sugarcane exceeds that of other intercrops. Net loss of N was also found less under the 100% N as compare to the rest of N levels and under sugarcane-based cropping system, there is heavy decline in N balance at post-harvest available N in the Sugarcane + finger millet intercropping system. Nitrogen levels and the sugarcane-based cropping system has not influenced the juice quality. Economics envisages reducing the N level is not advantageous for profitable system productivity. The best combination in terms of B:C ratio is sugarcane + amaranthus as the cost of cultivation is lower and the net return was higher.
يعتبر القمح أحد أهم مصادر البروتين ، الألياف ، المعادن والطاقة الحيوية اللازمة للإنسان ، وعلى الرغم من التقدم العلمي الذي ساهم في الوصول بإنتاج القمح حتى 9.5 مليون طن متري بالسنة إلا أن هذه الكمية لم تف إلا في حدود 20-35% من نقطة المجاعة العالمية لهذا تسعى كل الأنظار إلى الوقوف على محددات الإنتاج وممارسة ضغط عليها لكي تصل إلى معدل إنتاج بوحدة المساحة يساهم في تخفيض الفاقد لهذا المحصول وتعتبر الحشائش أحد أهم محددات الإنتاج وتشارك الحشائش النجيلية بقدر كبير من هذا الخفض وذلك بسبب التشابه بينها وبين المحصول في المتطلبات الزراعية والبيئية . لذا فإن هذه الدراسة تهدف لمعرفة أثر منافسة بعض الحشائش النجيلية مثل الشوفان البري (Avena fatua) والصامة (Lolium multiflorum) وأبورويس (Phalaris minor) عندما تزرع مع المحصول تبعاً للتصميم الإحلالي لدراسة منافسة الحشائش وبكثافة حشائش قدرها 45 بذرة/م2 و 190 حبة قمح/م2 ، صممت التجربة بتصميم القطاعات كاملة العشوائية بأربعة مكررات و 4 معاملات وزعت عشوائياً بحيث كانت هذه المعاملات خالية من الحشائش (شاهد) ، قمح + صامة ، قمح + شوفان وقمح + أبورويس . وبالنظر للنتائج أظهرت الصامة خفضاً معنوياً لكافة صفات نمو وإنتاج المحصول إذ تراوح محصول الحبوب عند منافسة الصامة لمعدل 1.2 طن/هـ مقارنة بالشاهد 3.0 طن/هـ ، مع ملاحظة أن حشيشة أبو رويس ساهمت في زيادة كافة صفات نمو ومحصول القمح إذ وصل محصول الحبوب إلى 4.5 طن/هـ .
Soils provide the foundation for food production, soil water and nutrient cycling, and soil
biological activities. With land use and land cover changes over the last century, soil fertility depletion, greenhouse gas emissions, irrigational water scarcity, and water pollution have threatened agricultural productivity and sustainability. An improved understanding of biochemical pathways of soil organic matter and nutrient cycling, and microbial communities involved in regulating soil health and soil processes associated with water flow and retention in soil profile helps design better agricultural systems and ultimately support plant growth and productivity. This book, Agroecological Approaches in Soil and Water Management, presents a collection of original research and review papers studying physical, chemical, and biological processes in soils and discusses multiple ecosystem services, including carbon sequestration, nutrients and water cycling, greenhouse gas emissions, and agro-environmental sustainability. The 15 chapters in this book cover various topics related to soil organic matter and nutrient cycling, soil water dynamics, and related hydrological processes across multiple soils, climate, and management. Several chapters highlight the impacts of land use, landscape position, and land-cover change on soil health and plant productivity. It also has chapters on greenhouse gas emissions as affected by agricultural management, and the roles of soil amendments like biochar and micronutrients. Novel water management strategies, including the use of coalbed methane co-produced water, biodegradable hydrogels, and livestock-integrated cropping to improve soil health are also discussed. The book further incorporates modeling studies on yield and greenhouse gas emissions and presents a review of sustainable agricultural and water management practices.
Weed competition causes serious economic losses to maize production. Timely and accurate assessment of pressure from competition is crucial for ecological weed management. In this work, we apply hyperspectral remote sensing (HRS) technology to conduct a competitive experiment in Harbin, China, in 2021, with 5-leaf maize as the study target. A weed competition assessment method that combines comprehensive competition indices (CCI) and deep learning is proposed. For the comprehensive competition assessment, the relationship between different weed competitive pressures (Levels 1–5) and changes in the structural and physiological information of maize was analyzed. The accumulative/transient competition indices CCI-A and CCI-T were designed for accurate quantification. The results showed that parameters such as plant height, stalk thickness and nutrient elements of maize decreased with increasing competition level. Parameters, such as stomatal conductance and transpiration rate, showed a fluctuating change of increasing and then decreasing with increasing competition level. Compared with the traditional relative competitive intensity (RCI), the standard deviation of CCI is 0.303 and 0.499. The dispersion effect of CCI is better and more suitable for quantifying the competition response. HRS images combined with 3D-CNN model were then applied to reveal the spectral response to different weed competition pressures (Levels 1–5) and to make early predictions of weed competition. The first-order derivative showed that the spectral reflectance exhibited significant differences at 520–525 nm peak, 570–655 nm trough, and near 700 nm red edge. For hyperspectral spatial-spectral features, the 3D-CNN model is proposed for prediction of competing indices CCI. In addition, the VIP method is used to select the characteristic wavelengths. The 3D-CNN model achieves a prediction accuracy of RMSE = 0.106 and 0.152 using 13 feature bands, which can accurately quantify the subtle changes in competition indices. Overall, this study shows that the combination of CCI and deep learning can provide a multivariate and comprehensive assessment of weed competition pressure.
Declining productivity and scarcity of cultivable land in smallholder systems call for exploring sustainable intensification options to increase productivity. Field experiments were conducted at five sites (sites 1–5) of Sidama region, southern Ethiopia in 2018 and 2019 to determine the effects of cropping systems on maize (Zea mays L.) and common bean (Phaseolus vulgaris L.) productivity. The intercropping of common bean with maize at varying planting times (simultaneous, relay) and number (frequency) of legume intercropping (once or twice) per growing season were compared with monocultures of the components in randomized complete block design with four replications. Cropping system affected the agronomic parameters (pod number plant−1 and 100‐seed weight) of common bean, more so than maize. Specifically, the results revealed that cropping systems affected both maize and bean yields, although the magnitude of the effect varied with sites. The highest maize yield was recorded in fertilized monoculture maize at sites 1, 2 and 5, and in relay and sequential bean intercropping at sites 3 and 4, respectively. Moreover, the highest bean yields were obtained in double common bean monoculture whereas, the lowest yields were recorded in relay intercropping. The total LER ranged from 1.2–1.8 and partial LER of maize was higher than that of common bean. Sequential intercropping (sites 1, 2 and 5) and relay intercropping (sites 3 and 4) were economically more beneficial than the other cropping systems. Therefore, farmers could benefit more from maize‐bean intercropping systems than monocultures in areas where maize is a staple crop. This article is protected by copyright. All rights reserved
In some biological experiments species are grown in monoculture and in all combinations of two in order to investigate competition effects. There is suggested a quantative definition of competition effects and a consequent analysis.
Two experiments are described in which the possible yield benefits of mixing maize and beans were examined under intensive farming conditions. A ‘replacement series’ of pure maize, two-thirds maize/one-third beans, one-third maize/two-thirds beans and pure beans was used at four plant populations. A high level of nitrogen was applied on the maize to eliminate the effects of nitrogen transfer from the beans.
Yields of the mixtures were up to 38% higher than could be achieved by growing the crops separately. It is concluded that this occurred because the mixtures achieved a greater utilization of environmental resources; it is suggested that, because of the marked height differences of the two crops, an increased utilization of light was probably a major contributing factor. The need for high populations in mixtures is indicated, partly because the largest yield increases were achieved at high populations and partly because the mixtures required a higher population pressure to produce their maximum yield.
The maize was found to have the higher relative competitive ability, and this increased with increase in plant population pressure. It is suggested that this was probably due to the shading effect which the maize had on the beans. The effects of a change in relative competitive abilities, or in relative selling prices, on the optimum proportion of two species in a mixture are also considered.
Data from 94 experiments on sorghum/pigeonpea intercropping were examined for evidence that the stability of yield is greater with intercropping than sole cropping. Stability of the major component (sorghum) was examined by calculating the distribution of yields; stability of the overall intercropping system was examined by calculating coefficients of variation, by computing regressions of yield against an environmental index, and by estimating the probability of monetary returns falling below given ‘disaster’ levels. All these approaches have some merit; taking the last as an example, it was found that for a particular ‘disaster’ level quoted, sole pigeonpea would fail one year in five, sole sorghum one year in eight, but intercropping only one year in thirty-six. Intercropping gave yield advantages under a wide range of environmental conditions and there was no significant evidence that advantages were greater under stress. This is discussed in relation to possible mechanisms contributing to greater yield stability.
An experiment is described in which the possible yield benefits of mixing dwarf sorghum and beans were examined under intensive farming conditions. A ‘replacement series’ of pure sorghum, two-thirds sorghum/one-third beans, one-third sorghum/twothirds beans and pure beans was used at four plant populations. A high level of nitrogen was applied to the sorghum to eliminate the effects of nitrogen transfer from the beans.
Yields of the mixtures were up to 55% higher than could be achieved by growing the crops separately. As with some earlier maize/beans experiments (Willey & Osiru, 1972), it is concluded that these yield increases must have been due to a greater utilization of environmental resources. It is suggested that the main factors which made this possible were probably the different rooting depths of the two crops and their different growth cycles.
In agreement with the earlier experiments, mixtures which consisted of two-thirds sorghum/one -third beans gave greatest yield increases at high populations and also had a higher optimum population than the pure stands. However, no such trends were apparent in the mixtures which consisted of one-third sorghum/two-thirds beans.
For both species intra-specific competition was greater than inter-specific competition. In contrast to the earlier maize/beans experiments, the relative interspecific competitive abilities of the species changed with change in the initial proportions of species in the mixtures. In the two-thirds sorghum/one-third beans mixtures the sorghum was the more competitive species, whilst in the one-third sorghum/two-thirds beans mixtures the bean was the more competitive species. Also in contrast to the maize/beans experiments, these relative competitive abilities were not affected by change in theoverall plant population pressure.