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Effect of soil solarization on weed growth and yield of kharif groundnut (Arachis hypogaea)
Abstract
A field investigation was carried out at UAS, Bangalore during 1995 and 1996 to study the effect of soil solarization on weed growth and yield of groundnut. The increase in soil temperature due to transparent polyethylene of 0.050 mm and 0.075 mm and black polyethylene was 9.5°C, 8.1 to 8.8°C and 2.0 to 3.4°C, respectively over control. There was a significant reduction in weed count and weed dry weight even up to the harvest of groundnut due to solarization with transparent polyethylene. The transparent polyethylene of 0.050 mm was superior than of 0.075 mm. Solarization for 45 days with transparent polyethylene caused maximum reduction in weeds. The black polyethylene did not help in suppressing weeds and was on par with control. Maximum pod yield was recorded by weed free check (21.26 q/ha) but on par with transparent polyethylene 0.050 mm for 45 days (20.64 q/ha).
... In India, the increase in soil temperature over that of control was 8.1-9.5°C (Mudalagiriyappa et al. 1999). It has been demonstrated that transparent plastics promote a relatively large net radiation at the soil surface, increase soil heat flux and, as a consequence, the minimum and maximum soil temperature are increased. ...
... Several studies have evaluated the effect of plastic thickness on solarization efficiency (Saleh et al. 1990, Habeeburrhman and Hosmani 1996, Marenco and Lustosa 2000, Mudalagiriyappa et al. 1999. In Jordan, Saleh et al. (1990) found that black plastic with medium thicknesses (60-80 m) increased soil temperature than thinner (40, 60 m) and thicker plastics (100, 120, and 200 m). ...
... In Jordan, Saleh et al. (1990) found that black plastic with medium thicknesses (60-80 m) increased soil temperature than thinner (40, 60 m) and thicker plastics (100, 120, and 200 m). In addition, Mudalagiriyappa et al. (1999) showed that solarization with 50 m transparent polyethylene attained greater pod yield in kharif groundnut in India than 75 m of the same plastic and than black sheets. Habeeburrhman and Hosmani (1996) concluded that solarization with 50 mum transparent polyethylene resulted in greater grain yield in kharif sorghum and greater reduction in weed biomass than 100 m transparent and black sheets. ...
Agricultural polymers are known since the 1950's and their uses were limited because of the high prices. But, recent retail prices became more affordable due to extensive research and generated private sectors on this new technology. For instance, highly crossed - poly - acrylamide potassium based (HCPAM-K) hydrophilic gel, was found useful to improve water absorption capability and availability of sand dunes for medium saline water. Most of cultivated farms at Al-Hassa oasis, Saudi Arabia depend on use of ground water as source for irrigation, where ground water is a limited resource and due to continuous pumping by huge quantities for irrigation and almost zero recharging, dramatic annual depletion is unavoidable. Introduce new techniques of water conservation to the agriculture industry, makes sense, save water and energy. One of recent promising technologies is use of artificial soil conditioners, such as polymers. In this study an experiment was conducted, to investigate effects of potassium based highly crossed polyacrylamide (HCPAM-K) hydro-gel polymer, on water holding capacity and percolation rate of three natural soils at Al-Hass oasis, using different irrigation water quality. Preliminary results indicated that the amount of water adsorbed at 0.0MPa pressure by sandy soil was increased by 33% with additions of 0.4% polymer. When the pressure was increased from 0 to 0.03MPa, these additions enabled the sandy soil to retain more water up to 150%. This increase in water retention can reduce the amount of water otherwise lost by deep percolation. Moreover, the released amounts as compared to adsorbed soil water amounts at 0MPa pressure, were 67%, 88% and 78% for clayey, sandy and polymer treated sandy soils respectively. This also indicated that sandy soil structure was improved and its adsorption ability increased by 10%, due to additions of polymer, manure and clayey soil.
... It is closely related to the practice of anaerobic soil disinfestation [18] but is not intended to result in prolonged anaerobic soil conditions. Tarping can decrease subsequent weed seed germination [19], but it is not always effective [20,21]. The few studies that have compared solarization and tarping for weed control suggest that solarization is usually more effective than tarping [20,22,23], likely due to higher soil temperatures achieved under solarization [24]. ...
... Tarping can decrease subsequent weed seed germination [19], but it is not always effective [20,21]. The few studies that have compared solarization and tarping for weed control suggest that solarization is usually more effective than tarping [20,22,23], likely due to higher soil temperatures achieved under solarization [24]. ...
Stale seedbeds are commonly used by organic vegetable farmers to reduce in-season weed density. The primary purpose of this study was to evaluate the efficacy of soil solarization (clear plastic) with subsequent flaming for stale seedbed preparation. A secondary objective was to compare the efficacy of solarization with tarping (black plastic). Solarization is an established weed management practice in warmer climates, but its efficacy in the humid continental Northeast USA was unknown. We hypothesized that solarization during May-June in Maine, USA would increase weed emergence, and could thereby contribute to depletion of the germinable weed seedbank and, with subsequent flaming, creation of an improved stale seedbed. We expected that firming soil with a roller prior to solarization would further increase weed emergence. Across four site-years of replicated field experiments and two on-farm trials we found that, contrary to expectations, 2 weeks of solarization reduced apparent weed emergence (density) in comparison to nonsolarized controls by 83% during treatment, and 78% after 2 weeks of observation following plastic removal and flaming. Rolling did not significantly affect weed density. Soil temperatures were elevated in solarized plots, reaching a maximum of 47◦ C at 5 cm soil depth, compared to 38◦ C in controls. Weed community analyses suggested that solarization might act as an ecological filter limiting some species. Addressing our secondary objective, two replicated field experiments compared the efficacy of solarization with tarping applied for periods of 2, 4, and 6 weeks beginning in July. Across treatment durations, solarization was more effective than tarping in one site-year, but tarping outperformed solarization in the other; this discrepancy may be explained by differences in weed species and soil temperatures between experiments. Overall, solarization and tarping are promising stale seedbed preparation methods for humid continental climates, but more work is needed to compare their relative efficacy.
... Tarping, also known as occultation (Fortier, 2014), is the practice of using black plastic silage tarps applied to the soil for several weeks prior to planting as a method for stale seedbed preparation. Tarping can decrease subsequent weed seed germination (Standifer et al., 1984), but it is not always effective (Hunter, Callaway, Rayburn, & Coffman, 2016;Mudalagiriyappa, Nanjappa, & Ramachandrappa, 1999). The few studies that have compared solarization and tarping for weed control suggest that solarization is usually more effective than tarping (Abu- ...
... Irmaileh & Thahabi, 1997; Mudalagiriyappa et al., 1999;Singh, 2006), likely due to higher soil temperatures achieved under solarization (Horowitz et al., 1983). However, in one study conducted during the fall in Israel, tarping outperformed solarization (Rubin & Benjamin, 1983), perhaps because soil temperature during this relatively cool season was insufficient for weed control via solarization. ...
Climate change is expected to impact weed communities in Maine, and the efficacy of tools and tactics farmers use to manage them. Through seedbank sampling and surveys of Maine organic farms, we identified currently rare weeds that are known to be especially abundant or problematic in warmer areas of the USA and might therefore represent an emerging agronomic risk. Many ecological weed management strategies that focus on depleting the weed seedbank are expected to remain effective in a changing climate, and become increasingly important as efficacy of cultivation and some herbicide applications diminish or become more variable. Through field experiments, we evaluated the efficacy of one seedbank management strategy, soil solarization (clear plastic) for stale seedbed creation. We found that two weeks of solarization followed by flaming created an effective stale seedbed, reducing subsequent weed density by 78% as compared to a control prepared with flaming only. In response to farmer questions, we measured solarization’s impacts on soil microbiota, and compared its weed control efficacy to that of tarping (black plastic). Soil biological activity was somewhat reduced by solarization, though results are likely temporary. Solarization was more effective than tarping in one site-year, but tarping outperformed solarization in the other. Overall, solarization is a promising weed management strategy for high-value crops, and one that is likely to remain effective in Maine’s changing climate. Maine is home to a growing population of beginning farmers, who face steep learning curves related to weed management. As a first step toward improving beginning farmer education, we constructed a digital tool called WEEDucator designed to engage users in interactive learning related to ecological weed management. Through a structured educational intervention we found that WEEDucator improved knowledge of weed ecology and management among agriculture students, and was ranked as a preferred learning method. Overall, the findings of this dissertation can aid in the development of outreach materials on climate-resilient ecological weed management practices suitable for farmers in Maine.
... Many researchers have tested PE mulch materials at different thicknesses to increase the efficiency of solarization. Researchers have reported that thinner mulch materials show more effective solarization success (Barakat, 1990;Mudalagiriyappa et al., 1999;Stapleton, 2000;Candido et al., 2011;Cascone et al., 2012). D'Emilio (2017a) stated that totally impermeable films (TIF) and virtually impermeable films (VIF) have better spectroradiometric properties and higher temperatures than low density polyethylene (LDPE) Black and other colored plastics are not suitable for solarization process because instead of allowing radiation and heating the underlying soil, solar energy is absorbed and diffused back into the atmosphere. ...
... Chase et al. (1999) stated that the uncolored PE material is more effective at increasing the temperature at different soil depths than the black one. Researchers have indicated that the most suitable material for solarization applications is uncolored plastic material (Mudalagiriyappa et al., 1999;Stapleton, 2000;Komariah et al., 2011;Granados et al., 2012). ...
Soil solarization is a non-chemical method used to destroy soil borne pathogenic, harmful, and weed seeds in agricultural field and greenhouses. Solarization is generally applied in regions with high summer air temperatures and high solar radiation. Organic materials obtained as a result of the pyrolysis process in an anaerobic environment is called biochar. It can be produced from a wide range of plant and animal origin biomass sources. Lettuce plants are an important vegetable species grown after the application of solarization because of their high value and compatibility with autumn growing. Researchers reported that lettuce yields increased following soil solarization.
The aims of this work were to examine different mulch materials and addition of biochar (a new approach in soil solarization) of soil temperature change, and determine which month is more effective according to temperature difference, and also effect of solarization application on yield, quality, and leaf nutrient content characteristics of lettuce plant. The experimental site was located at the University of Suleyman Demirel University in Isparta and the study was conducted during summer and autumn of 2016. Two different polyethylene (PE) mulch materials have been tested. Four different treatments and non-solarization were performed in this research. There were PE mulch, bubble PE mulch, PE + biochar, bubble PE+ biochar and non-solarization treatments. In the parcels where biochar application is used, it was applied 150 g m−2 of the soil surface as a thin mulch.
Biochar added bubble solarization mulching film was determined to be more effective with regard to temperature increase and heat conservation in comparison with the traditional mulch material. Solar radiation played an important role in rising soil temperature with mulch material. With the fall of solar radiation in August, temperatures under mulching films decreased. But, temperature inside the greenhouse and the temperature of the bare soil did not change or it was affected less. Yield increase of 100% was attained for lettuce yield increase with biochar added bubble solarization mulch in comparison with the control. Thus, the study reached the determined objective and it has been determined that biochar use plays an important role in the effectiveness of solarization applications.
... Hence the experiment regarding the field evaluation and performance of three bio agentsalong with soil solarization was decided to conduct in this polyhouse for two consecutive years (2019-2020 and 2020-2021) for bell pepper variety Rijk Zwaan Bachata Rz F1. We provided the farmer from our project the transparent polythene film of 25 microns thickness because they are most effective in trapping the solar radiation [33], [32], [44]. This was done after the slight irrigation through drip in the month of May for four weeks leaving the control plots and the polyhouse was completely sealed (figure 2 and 3). ...
... The hot temperatures experienced under the clear plastic can cause weed mortality and can also reduce the viability of weed seeds residing in the top 5 cm of the soil profile (Peachey et al. 2001;Samtani et al. 2017). Numerous studies have shown the utility of soil solarization on reducing weed density and biomass in arid environments (Mudalagiriyappa et al. 1999;Singh 2006). Solarization with clear plastic for 30 days prior to crop planting reduced weed densities, weed biomass, and increased soybean yield in field studies in India (Singh 2006). ...
Effectively managing weeds in organic vegetable production continues to be challenging and costly. Cultivation, often referred to as physical weed control (PWC), is foundational for organic farmers; however, efficacy tends to be low and highly variable. Additionally, some crops are slow to germinate, and thus have poor competitive ability against weeds and high mortality from cultivation. This can result in high costs for hand-weeding labor, abundant seed rain into the soil, and a recurring, often increasing, weed problem. These challenges may be addressed by “stacking” tools to increase weed control efficacy, integrating targeted seedbank management strategies to reduce the germinable weed seedbank, and characterizing crop cultivar early growth traits to better understand crop tolerance to different tool mechanisms. ii Chapter one reviews weed management from the perspective of small-scale organic vegetable farms and the unique challenges they face. Weed control objectives, such as minimizing weed seed rain and reducing labor costs, seed- and seedling-focused management like tarping and hand-tool options, and future research needs for small-scale farms are discussed. Chapter two assesses a weed management systems experiment combining tool stacking with seedbank management and how these practices can affect weed control efficacy and the germinable weed seedbank, respectively. Tool stacking helped increase efficacy and lower weed seedling densities during the growing season, while seedbank management reduced the germinable weed seedbank and contributed to higher crop yields in bush bean and table beet. Chapter three builds upon the previous chapter by examining how tool stacking can be used with the Terrateck Double Wheel Hoe, a unique hand tool. The effects of single tools and tool stacking on crop mortality and weed control efficacy were examined in bush bean and table beet. Tool stacking increased weed control efficacy in both crops, and although stacking did not result in higher crop mortality in bush bean, table beet mortality was high. Chapter four assesses the concept of “cultivation tolerance” with nine carrot cultivars, selected to represent large, average, and relatively small plants. Root and shoot characteristics were measured in greenhouse experiments, and carrot mortality and yield from cultivation were measured in field experiments. Few differences in early growth characteristics were found at two-true leaves, and unexpectedly, no differences in cultivar mortality were detected in the field.
... Soil moisture favors cellular activities and growth of soilborne microorganisms and weed seeds, thereby making them more vulnerable to the lethal effects of high soil temperatures associated with soil solarization. 4. Plastic Tarp: Transparent polyethylene films are more efficient than black films in trapping solar radiation (Horowitz et al., 1983;Bhasker et al., 1998;Mudalagiriappa et al., 1999) and reducing weed emergence (Table 1). Chase et al. (1998) found that soil solarization through transparent polyethylene reduced the emergence of purple nutsedge ( Cyperus rotundus L.) (5 plants/m 2 ) as compared to black low-density polyethylene (35.7 plants/m 2 ) after 5 weeks. ...
... Nanjappa et al. [89] confirmed that solarization with TPE resulted in higher soil temperature of 54.33°C at 5 cm soil depth and there was 13°C rise in temperature as compared to control. Mudalagiriyappa et al. [90] reported that 0.05 mm TPE mulched plots recorded lower weed count and weed dry weight than the 0.10 mm TPE in groundnut. Physical weed management methods are effective, economic and environmentally safe. ...
As per FAO, the regions receiving rainfall less than potential moisture loss through evaporation and transpiration with aridity index <0.65 are considered as drylands. These lands are characterized by low and erratic rainfall, water scarcity, high temperature, high potential evapo-transpiration, low humidity, high wind velocity coupled with unique bio-physic and socio-economic characteristics. Drylands occupy nearly 40 % earth land surface which is inhabited by nearly 35 % population of the world. But it has the highest level of poverty (around 47 %). In India, dryland accounts for about 57 % of total cultivated area that supports 40 % human and 60 % livestock population, but crop production is not stable. Therefore stable crop production is of prime importance to achieve sustainable livelihoods in drylands. Conservation of precipitation, nutrients, natural resources and increasing resource use efficiency can play vital role to achieve stable crop production and livelihood security. Among many factors that adversely influence resource use efficiency and crop production, severe weed infestation is most important. Weeds have the ability to survive under adverse condition, as they extract more water and nutrients from the soil, thereby reduce crop yield by 37 to 79 % in dryland agriculture. Weeds being more aggressive, adaptive and persistent pose serious threat to crop production and are difficult to control below economic threshold level with single weed management practice. Hence, more emphasis is needed to develop multiple and integrated weed control strategies in a holistic manner for sustainable crop production and livelihood security in drylands.
... This better performance of the crop in terms of growth and yield could be attributed to the reduced incidence of weeds and dry weight of weeds in these treatments. Yaduraju and Ahuja (1990), Mudalagiriyappa (1999) and Soumya et al. (2004) also reported increase in yield of groundnut under weed-free situation. ...
A field experiment was conducted during 2004 and 2005 at Bangalore to work out the economics of soil solarization on break-even basis with different thicknesses (0.05 and 0.01 mm) of transparent polyethylene (TPE) in groundnut (Arachis hypogaea L.) ñ bell pepper (Capsicum annum L.) sequence. Soil solarization with TPE 0.05 mm covered twice in the same season recorded significantly higher pod yield of groundnut (2.36 t/ha) and fruit yield of bell pepper (15.1 t/ha), followed by TPE 0.05 mm covered once in the same season (2.27 t/ha and 12.0 t/ha respectively) and TPE 0.10 mm covered twice (2.17 t/ha and 12.6 t/ha). Similarly, leaf area/plant and yield attributes, viz. number of pods/plant (23.0) and number of fruits/plant (6.4) were also superior in soil solarization with 0.05 mm twice, TPE 0.05 mm once (21.7 and 5.3 respectively) and TPE 0.10 mm twice (22.1 and 6.0). Significantly lower number of weeds and weed dry weight was recorded with TPE 0.05 mm twice in both groundnut and bell pepper crop sequence. Repetitive use of TPE 0.05 mm for two times in the same season recorded higher net income (Rs 139.95 ×10 3/ha) and B : C ratio (3.86) followed by TPE 0.05 mm for three times and TPE 0.10 mm for two times continuously in the same season. Soil solarization with TPE 0.05 mm thickness twice in the same season for groundnut ñ bell pepper sequence was found to be highly productive and most economical practice.
... Soil solarization has been considered as an appropriate, non-chemical alternative to methyl bromide fumigation. Several investigators have demonstrated the efficiency of solarization in controlling the weeds of different crops at several places in the world, especially in the hot, arid regions (Mauromicale et al. 2001;Nimje & Agrawal 2002;Soumya et al. 2003;Kalaisudarson & Sundari 2004). However, several studies have reported that weeds respond differently to solarization in different places in the world, such as Italy (Tamietti & Valentino 2000), Turkey (Campiglia et al. 2000;Benlioglu et al. 2005), India Chopra & Chopra 2004),Tunisia (Triki et al. 2001), the USA (Elmore 1991), Israel (Horowitz et al. 1983), and Argentina (Bustamante et al. 2003). ...
The efficacy of solarization in weed control under field conditions of the United Arab Emirates was evaluated by two methods: on-farm weed assessment and a seed germination test. In the on-farm weed assessment method, the weed frequency, density, and dry weight were compared in the solarized and non-solarized plots that were cultivated with cabbage. Prior to solarization, the soil was artificially infested with the seeds of 10 weeds. Generally, the densities of seven species and dry weights of five species were significantly lower in the solarized plots as compared to the control. Launea mucronata, Capsella bursa-pastoris, and Echinochloa colona were very sensitive to solarization, as they did not appear in the solarized plots. However, Portulaca oleracea and Melilotus indica were not significantly affected by soil solarization. In the second method, the germination was assessed for the seeds of four weedy species buried at three depths for different durations of solarization. The results confirmed the great sensitivity of L. mucronata and C. bursa-pastoris seeds to solarization, as all had not germinated after 15 days of solarization, even at the 15 cm depth. The seeds of E. colona, however, were less sensitive after 15 days of solarization, especially at 7.5 cm and 15 cm, respectively. The seed germination method confirmed the resistance of the P. oleracea seeds to solarization. The results emphasized the importance of the germination test to provide accurate predictions about the spatial and temporal changes of the soil seed bank in solarized farms. This would help to determine the optimal duration of solarization in each farm, depending on the kind of weeds infesting the farm.
Amaç: Bu çalışmada amaç, farklı solarizasyon malç malzemeleri ve biochar uygulamasının marul bitkisinin mineral beslenmesine etkisi belirlenmeye çalışılmıştır.Yöntem ve Bulgular: Sera koşullarında 2 yıl yürütülen çalışma, 2 farklı solarizasyon örtüsü ve biochar uygulamaları ile gerçekleştirilmiştir. Solarizasyon uygulamasından sonra her bir parselde marul yetiştirilmiştir. Hasat dönemi sonunda, hasat edilen bitkilerde kuru ağırlık değerleriyle kimi besin elementi konsantrasyonları belirlenmiş, ayrıca bitkilerce topraktan kaldırılan besin elementi miktarları hesaplanmıştır. Elde edilen sonuçlara göre; genel bir değerlendirme yapıldığında her iki yıl için de bitki kuru ağırlığı üzerine en etkili uygulamaların solarizasyon ve biochar uygulamalarının birlikte yapıldığı uygulamalar olduğu bunun yanında en etkisiz uygulamaların ise kontrol konularını içeren uygulamalar ile klasik solarizasyon yapılan konuların olduğu belirlenmiştir.Genel Yorum: Topraktan kaldırılan besin elementleri üzerinde en etkili uygulamaların balonlu solarizasyon+ biochar ve solarizasyon + biochar uygulamaları olduğu, en etkisiz uygulamaların ise kontrol ve solarizasyon uygulamaları olduğu belirlenmiştir.Çalışmanın Önemi ve Etkisi: Klasik solarizasyon örtü malzemesinden elde edilen sonuçlara kıyasla, balonlu solarizasyon örtü malzemesi ve biochar ekli solarizasyon uygulamaları marul mineral beslenmesi açısından daha etkili olduğu sonucuna ulaşılmıştır. Bu çalışmadan elde edilen sonuca göre, solarizasyon uygulamalarında biochar katkısı yardımıyla daha etkin bir yetiştiricilik yapılabilecektir.
Soil solarization with TPE 0.025 mm for 45 days increased the soil temperature to an extent of 10.6° and 8.6°C over non- solarized at 5 and 10 cm depth of soil, respectively. Thinner TPE was more effective than thicker one. All SS treatments retained higher soil moisture than non-solarized. Significantly the least count, dry weight and dry biomass of weed were recorded under TPE 0.025 mm for 45 days at harvest, whereas WCE was recorded maximum in both the crops under this treatment. Growth attributes were registered maximum under TPE 0.025 mm for 45 days in both the crops. Significantly higher pod yield (27.68 q/ha) and haulm yield (48.39 q/ha) of groundnut and total tuber yield (30.44 t/ha) and haulm yield (66.86 q/ha) of potato was recorded under TPE 0.025 mm for 45 days than rest of the treatments. Use of 0.025 mm thin TPE spread for 45 days was found most effective in controlling weeds as well as producing higher yield and system productivity; and securing maximum net returns, BCR and profitability in groundnut-potato cropping systems.
A field experiment was conducted during 1998 and 1999 at Jabalpur, Madhya Pradesh, to study the effect of different periods of soil solarization and weed-control measures on weed incidence and productivity of soybean [Glycine max (L.) Merr.]. Mean maximum soil temperature in mulching with transparent polyethylene was 56.4°C at surface, 53.6°C at 5 cm, 44.3°C at 10 cm, and 39.4°C at 15 cm soil depths which was higher than non-solarized plots by 10.2, 9.4, 5.1 and 3.4°C respectively. Soil solarization for 5 weeks reduced the emergence of jungle rice [Echinochloa colona (L.) Link] by 95%, wild jute (Corchorus) by 83%, common dayflower (Commelina communis L.) by 80% and gripe weed (Phyllanthus fraternus Webster; syn P. niruri Hook. f., non L.) by 58%. Solarization for 5 weeks resulted 82% and 90% reduction in weed population and weed dry weight respectively. Solarization for 5 weeks being at par with 4 weeks also produced significantly higher leaf area and crop dry matter/plant over rest of the treatments. Solarization with transparent polyethylene markedly increased the yield attributes, viz pods/plant, 1 000-seed weight and seeds/pod, and seed yield of soybean. The highest seed yield of soybean (1 645 kg/ha) was recorded with solarization for 5 weeks, being 110% higher than nonsolarized control. Presence of weeds throughout the growing season caused 35% loss in seed yield of soybean. Amongst the weed-control measures, the highest seed yield of soybean (1 478 kg/ha) was achieved with 1 hand-weeding at 20 days crop stage.
Groundnut crop is highly susceptible to weed infestation because of its slow growth in the initial stages upto 40 days, short plant height and under ground pod bearing habit. Groundnut- weeds comprise diverse plant species from grasses to broad-leaf weeds and sedges, and cause substantial yield losses (15-75%) which are more in rainfed Spanish bunch type than in irrigated Virginia type groundnut. Besides this, weeds are preferred host of several insect-pests, and the vectors of many important organisms causing diseases in groundnut. Weeds also affect groundnut through the production of harmful allelochemicals. Thus, weed control is the foremost critical production factor in groundnut cultivation and in this revie w, various physical, chemical, mechanical and cultural methods that curtail the growth and spread of weeds have been discussed. Herbicides were found to be selective in controlling many weeds in monocropping as well as in cropping systems. Herbicides, though, selective, efficient and cost effective weed control measure in controlling weeds in groundnut, the maximum benefit can be achieved by combining herbicides with manual, cultural and mechanical weed control methods. These methods of weed control also vary with the groundnut growing situation and the cropping systems. In this review, an effort was made to compile the information on feasible weed management practices for groundnut in India and the future strategies to very simple, cheap, effective, and environmentally safe integrated approaches.
The search for new effective, economic and eco-friendly methods for controlling weeds is a continuous process, as none of the existing methods can be used in all situations. Manual weeding though effective and commonly used in many under developed and developing countries is expensive and time consuming, and hence economically restricted to certain crops and seasons. Use of herbicides for controlling weeds is very effective and economical but has been criticized by the environmentalists for polluting the ecosystem. Besides, there is inherent danger of resurgence of weeds resistant to herbicides. Use of solar energy as soil solarization for controlling soil-borne pests including weeds, pathogens and nematodes has potential for reducing the dependency on chemicals.
Mulches in five combinations of clear plastic, black plastic, and undecomposed leaves covered by or on top of black or clear plastic film to modify soil temperature, were used to study the enzyme activity of the soil and numbers of bacteria able to produce degradative enzymes. Yield of pepper and broccoli planted through the mulches was measured.
The numbers of bacteria in the soil able to excrete protease, phosphatase, cellulase, and lipase were correlated with one another suggesting that the same group of organisms excreted the different enzymes. The activity of enzymes in the soil was similarly correlated. Bacterial urease-producers and the urease activity in the soil were not correlated with the number of other enzyme producers or activity of other enzymes in soil suggesting an independent population of urease producers degraded the urea fertilizer used. Temperature differences of 11–14°C provided by the various mulches appeared insufficient to create important differences in populations and biochemical activities of soil bacteria.
Yield of broccoli was greatest early in the season in soil warmed under black polyethylene plastic and later in the season in the soil cooled with leaf mulch over black plastic. Yield of pepper was greatest in mid-to-late summer on soil warmed with black plastic, but the highest yield was obtained in early fall in soil with clear and black plastic over leaf mulch.