Article

Soil Acidity Management by Farmers in the Kenya Highlands

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Abstract

Declining soil fertility attributed to soil acidity is a major soil productivity problem in sub-Saharan Africa. A study was carried out in nine counties across the Kenya highlands, namely Meru, Embu, Kerugoya, Nyeri, Kiambu, Kinangop, Siaya, Busia and Eldoret, where the problems associated with soil acidity are prominent. The study aimed at assessing farmers’ awareness of soil acidity, and establishment of common acidity management practices following administration of structured questionnaires. From the information gathered through personal interviews via questionnaires, <37% of the farmers were attached to a farmers training group in all study sites; among them, <4% were aware of soil acidity problems and <8% had carried out chemical analysis of their soils. The farmers who had applied lime at least once on their farms were <3% in all sites. Most farmers (>80%) used both inorganic fertilizers and manure on their farms, with the majority using DAP, CAN and farmyard manure. On cultural soil fertility management, choice of subsequent crop wasdictated by sustainability rather than cropping system like rotation. There was a significant (P<0.05) negative relationship between livestock keeping and soil fertility management, with <30% of the farmers returning crop residues back to the farm. Most of them fed crop residues to their livestock. Only 8% of the farmers incorporated crop residues into the soil. There was a significant (P≤ 0.05) positive correlation between education level and inorganic fertilizer use in crop production. Farmer’s age and maize yields correlated negatively with each other. Additionally, farmers’ training programmes and frequencies positively influenced choice of inorganic fertilizers and levels of application. Training is therefore one of the most significant issues affecting soil fertility management in the Kenya highlands. To further enhance the understanding of soil acidity and fertility management in Kenya highlands, farmers training should be prioritized.

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... Most farmers do not have enough knowledge of their farms' soil fertility status (Muindi, et al., 2016). This means they run a risk of continuously adding the nutrients without any meaningful response on yields. ...
... The farming systems of upper eastern Kenya are relatively complex because of the high rainfall variability typical of the semi-arid tropics (Rao et al., 2011). Insufficient soil moisture is one of the greatest impediment to agricultural productivity (Muindi et al., 2016). Most crop productivity related research conducted in this region have been geared towards addressing soil moisture conservation through different rainwater harvesting approaches, or soil fertility amendments for enhanced crop production (Gichangi et al., 2007). ...
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Water harvesting technologies and soil conservation measures promote water-nutrient synergy and increase agricultural production in the dryland zones of sub-Saharan Africa. To alleviate water stress, soil fertility decline and reduce runoff, soil and water conservation measures are promising options whose impact on agricultural productivity has not been fully explored. The objective of the study was to assess the effect of using zai pits in combination with selected soil fertility ammendments. An experiment was conducted in Tharaka Nithi County, Kenya to assess effects of using Zai pits in combination with selected amendments on sorghum production. The experiment was set up in a Randomized Complete Block Design (RCBD) involving 12 soil and water conservation treatments with three replications per block. Experimental data were subjected to analysis of variance and mean separation done using least significant difference (LSD) at p < 0.05. Zai pit in combination with tithonia amendment had the highest yields of 4.30 Mg ha−1 during short rains season of 2013 while Zai pit in combination with cattle manure had the highest yield of 4.18 Mg ha−1 during short rains season of 2014. Conventional planting with full rate NPK had the highest benefit-cost ratio (BCR) of 3.58 while Zai pit without input had the least BCR of 0.99. The experiment showed that Zai pit technology contributed to increments of yields in comparison to conventional planting although its BCR was lower than conventional planting with similar amendments. However, both Zai pit and conventional practices should be used in combination with organic and inorganic amendments to enhance yields in sorghum production.
... Unresponsiveness has been attributed to the nutrient being strongly fixed in the soil (especially P), thus being unavailable to the plant (Fixen & Bruulsema, 2014;Muindi et al., 2015;Wilhelm, 2009). Most farmers do not have enough knowledge of their farms' soil fertility status (Muindi et al., 2016). This means they run a risk of continuously adding the nutrients without any meaningful response on yields. ...
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Low nutrients have been reported in potato-growing areas of Kenya, prompting a need for nutrient management research. A study was designed to determine the effect of omitting nutrients on potato growth, yield and harvest index. On-farm nutrient omission trials were set during the long rains (LR) and short rains (SR) of 2016 in which the treatments involve the judicious omission of N, P, K, S and B. Additional two treatments were included with one receiving all the nutrients and a control where no nutrients were added. The treatment was laid in a randomized complete block design with three replications. Potato yields reduced by 6.6 and 11.2 t ha−1 in N-omitted treatments in LR and SR, respectively, when compared to the one receiving all the nutrients, while omitting P resulted in respective yield reductions of 3.8 and 2.0 t ha−1. Stability analysis revealed that omission of N was more stable with a regression coefficient of 0.5; it was followed by P with a value of 1. Potassium, S and B were limiting nutrients only in some farms. N and P should continue to be included in potato nutrient management, while K, S and B should be added based on soil test.
... In highly acidic soils of pH below 5, Al 3+ is solubilized thereby inhibiting root growth and function and leaving plants more vulnerable to drought and mineral nutrient deficiencies (Lyza et al., 2013). In sub Saharan Africa, acid soils occupy 29% of the total land area (Muindi et al., 2015). ...
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ABSTRACT Aluminum (Al) toxicity causes high yield losses and is directly linked to acidic soils. Application of lime can ameliorate this problem, but it is costly and not feasible for small scale farmers as they need to purchase both seed and lime. Developing maize varieties that are tolerant to Al toxicity is cheaper and feasible for small scale farmers. The purpose of this research was to i) identify maize genotypes with tolerance to Aluminum toxicity, ii) evaluate the general and specific combining abilities for the inbred lines and crosses respectively, iii) investigate the type of gene action conditioning tolerance to aluminum toxicity in tropical maize, and iv) determine if shoot length can be used as an indirect selection criterion for Al tolerance. Fourteen maize inbred lines (CZL 083, L151, L552, CZL0814, CML312, L12, L3233, CML511, L917, L2, CML538, L5522, CML 457, and CZL04007) were evaluated in hydroponic conditions containing different concentrations of Al (0, 5, 10, 15 and 20mg/ L) in a 14 x 5 factorial completely randomized design with 3 replications at the University of Zambia, plant physiology laboratory. Five parameters were measured: root length, shoot length, number of root hairs, root and shoot biomass on eleventh day after seed placement. Highly significant differences (P=0.001) were noted for both root and shoot lengths. The results showed that inbred line CML 538 was highly tolerant while inbred line L151 was the most susceptible with mean lengths of 15.44 cm and 6.11 cm respectively. To address objective ii, eleven inbred lines were selected and mated in an 8 male (4 moderately tolerant and 4 susceptible) x 3 female (resistant) North Carolina Design II. Results revealed that GCA effects due to both males and females were highly significantly (P= 0.001) different from zero for root biomass. The shoot length GCA effects (8.75 and 12.81) due to both male and female respectively were significant (P=0.01). Similarly, the GCA effects due to females and males for root length were significant P= 0.01 and P=0.05 respectively. The SCA effects for the shoot length and root biomass were significant (P= 0.02). Both additive and nonadditive gene action were identified to be important for the root length as indicated by a Baker’s ratio of 0.49. The association of root length to shoot length was significant (correlation [r] = 0.72). Keywords: Aluminum, tolerance, General Combining ability, Specific Combining ability, Zea mays, Inbred lines, crosses.
... Approximately 40-50% of the World's total potential arable land consists of acid soils. The acid soils (pH ≤ 5.5) comprise approximately 30% of the total earth area and they are associated with high levels of exchangeable aluminium (Al), hydrogen (H), iron (Fe) and manganese (Mn) in soil solution [1,2,3]. They are also associated with toxicities to plant roots in the soil solution and corresponding deficiencies of the available P, molybdenum (Mo), calcium (Ca), magnesium (Mg) and potassium (K) [4][5][6][7][8]. ...
Article
Liming and phosphorus (P) applications are recommended practices for improving crop production in acid soils of the tropics. Although considerable work has been done to establish liming rates for acid soils in many parts of the world, information on the effects of lime on the forms of aluminium which actively sorb P in such soils is minimal. A greenhouse pot experiment was conducted at Waruhiu Farmers Training Centre, Githunguri to evaluate the effect of liming on oxalate and dithionate extractable aluminium in acid soils. Extremely (pH 4.48) and strongly (pH 4.59) acidic soils were evaluated. Four liming (CaO) rates namely 0, 2.2, 5.2 and 7.4 tonnes ha-1 for extremely acidic and 0, 1.4, 3.2, and 4.5 tonnes ha-1 for strongly acidic soils were evaluated. The experiment was laid out in a Randomized Complete Block Design (RCBD) and replicated three times. Data collected included: initial soil chemical properties, oxalate (Alo) and dithionate (Ald) aluminium levels. The tested soils had high exchangeable Al (> 2 cmol Al kg-1), Al saturation of (> 20% Al) and low extractable P values (< 15 mg P kg-1 soil). Liming significantly (p=.05) reduced Alo by 70% and 68% in extremely and strongly acidic soils respectively and Ald by 78% in both extremely and strongly acidic soils compared to control. Use of 7.4 tonnes ha-1 of lime in extremely acidic soils and 4.5 tonnes ha-1 of lime in strongly acidic soils significantly (p=.05) reduced both Alo and Ald by > 68% compared to no lime. It was, therefore, concluded that liming contributes to the reduction of soluble Alo and Ald in acid soils of the Kenya highlands leading to increased soluble P availability. Studies are required to provide short and long term optimal liming rates that reduce Alo and Ald without distabilizing availability of other nutrients in field conditions under wide range of acid soils.
... This can be attributed to the ability of contour terraces to improve soil and water management hence improved crop establishment, growth and yields. Similar trends of increased crop production hence alleviation of poverty and enhancement of food security after adoption of water management structures has been reported in South Africa by [47]. ...
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Inadequate quality-water is a major hindrance to rur al development and food security in arid and semi-arid areas of Kenya. Technologies that can promote water harvesting and conservation are, therefore, instrumental in increasing resilience in recu rring droughts and enhancing food security in these dry lands. A study was carried out in Kilifi sub- County in the coastal areas of Kenya one of the areas where food insecurity incidences are prevalent . The study aimed at assessing the influence of water management structures on food securi ty status among smallholder farming communities. Non experimental design using descriptive sur vey was adopted for the study. Data was analyzed using descriptive statistics and logistic reg ression to measure the contribution of water harvesting structures and irrigation to food securi ty status. Water harvesting structures examined were: contour terraces, water pans, trash line s, boreholes, and unploughed strips. The results indicated that 80% of the respondents were f ood insecure. The respondents who adopted boreholes and unploughed strips were 2% food secure whi le those who adopted water pans and Original Research Article Chege and Muindi; AIR, 8(3): 1-9, 2016; Article no. AIR.28888 2 trash lines were 4% food secure respectively. Additiona lly, those who adopted contour terraces were (8%) food secure compared to other water harvest ing structures. There was a significant (P=0.05) positive relationship between the water mana gement structures and food security This implies that contour terraces, water pans, water harvesti ng structures being economical, possession of title deed and land size are some of the most significant issues affecting food security in Kilifi Sub-county. To further enhance the understanding of food security and improve food insecurity status in Kilifi Sub-county, adoptio n of water harvesting structures should be promoted by all stakeholders.
... The research is in agreement with Babatunde et al. [21] who found out that middle aged household heads were energetic and were able to cultivated larger farms and obtain off-farm jobs for extra income compared to older and weak ones. Similarly, Muindi et al. [31] and Teklewold et al. [32] reported that young household heads adopted new farming technologies easier compared to older farmers. They further attributed the trend to fear of the unknown. ...
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Food security is critical to the economic, social, religious, political and cultural development Worldwide. It plays a great role in economic growth, poverty reduction and sustainable development in Kenya. A study was carried out in Kilifi sub- County in the coastal areas of Kenya, one of the areas where food insecurity incidences are prevalent. The study assessed the effect of household characteristics on food security status among smallholder farming communities through interview schedues. Non experimental design using descriptive survey was adopted for the study. Household and farm characteristics data was analyzed using descriptive statistics and logistic regression. The results indicated that 80% of all the farmers were food insecure. Elderly farmers were 1% food secure while adults were (40%) food secure. Households with at most two members were more food secure (10%) while households with >10 members least food secure (2%). Household heads withsecondary school level of education were more food secure (10%). Women were more food secure (12%) than males (8%). There was a significant (P= .05) positive relationship between food security and household heads age, marital status and education level. This implies that household heads age, education level and marital status, are some of the most significant issues affecting food security in Kilifi sub-county. To further enhance the understanding and improvement of food security status in Kilifi sub-county, initiation of both formal and adult education is necessary. This will improve households understanding, decision making and adoption of new agricultural innovations hence improved food production and food security levels.
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81-92. The study examined the constraints to utilization of pig production technology in Ashanti Region of Ghana. Primary data were collected using a set of structured and validated interview schedule from 80 pig farmers who were selected using multistage sampling techniques from selected villages and towns scattered in the region. Data analysis was carried out using frequency counts, percentages and Pearson Product Moment Correlation (PPMC). The result of the analysis showed that the major source of information of pig farmers to utilization of pig production technology was mostly through veterinary officers. The adoptions of improved technologies were associated with age, education, operational land holding, farm size, income from piggery, social participation, extension contact, farming experience, farm education exposure, scientific orientation, knowledge level, training and financial help received. These variables contributed 35.00% variation in the adoption gain in improved technologies in pig farming. The major recommendation that emanated from the study was, that to increase the level of adoption of improved technologies in pig farming, farmers were required to be exposed to as many as cosmopolite sources of information as possible, to make them aware of these technologies.
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This edition updates a narrative that has been at the forefront of soil science for more than a century. The first edition, published in 1909, was largely a guide to good soil management for farmers in the glaciated regions of New York State in the northeastern U.S. Since then, it has evolved to provide a globally relevant framework for an integrated understanding of the diversity of soils, the soil system and its role in the ecology of planet Earth. The 15th edition is the first to feature full-color illustrations and photographs throughout. These new and refined full color figures and illustrations help make the study of soils more efficient, engaging, and intellectually satisfying. Every chapter has been thoroughly updated with the latest advances, concepts, and applications. Hundreds of new key references have been added. The 15th edition, like preceding editions, has greatly benefited from innumerable suggestions, ideas, and corrections contributed by soil scientists, instructors, and students from around the world. Dr. Nyle Brady, although long in retirement and recently deceased, remains as co-author in recognition of the fact that his vision, wisdom and inspiration continue to permeate the entire book. This edition,1082 pages in length, includes in-depth discussions on such topics of cutting edge soil science as the pedosphere concept, new insights into humus and soil carbon accumulation, subaqueous soils, soil effects on human health, principles and practice of organic farming, urban and human engineered soils, cycling and plant use of silicon, inner- and outer-sphere complexes, radioactive soil contamination, new understandings of the nitrogen cycle, cation saturation and ratios, acid sulfate soils, water-saving irrigation techniques, hydraulic redistribution, cover crop effects on soil health, soil food-web ecology, disease suppressive soils, soil microbial genomics, indicators of soil quality, soil ecosystem services, biochar, soil interactions with global climate change, digital soil maps, and many others. In response to their popularity in recent editions, I have also added many new boxes that present either fascinating examples and applications or technical details and calculations. These boxes both highlight material of special interest and allow the logical thread of the regular text to flow smoothly without digression or interruption. For students: This book provides both an exciting, accessible introduction to the world of soils as well as a reliable, comprehensive reference that you will want to keep for your professional bookshelf. What you learn from its pages will be of enormous practical value in equipping you to meet the many natural-resource challenges of the 21st century. The book demonstrates how the soil system provides many opportunities to see practical applications for principles from such sciences as biology, chemistry, physics, and geology. Throughout, the text highlights the countless interactions between soils and other components of forest, range, agricultural, wetland, and constructed ecosystems. As the global economy expands exponentially societies face new challenges with managing their natural resources. Soil as a fundamental natural resource is critical to sustained economic growth and the prosperity of people in all parts of the world. To achieve balanced growth with a sustainable economy while improving environmental quality, it will be necessary to have a deep understanding of soils, including their properties, functions, ecological roles and management. I have tried to write this textbook in a way designed to engage inquisitive minds and challenge them to understand soils and actively do their part as environmental and agricultural scientists, in the interest of ensuring a prosperous and healthy future for humanity on planet Earth. It is my sincere hope that this book, previous editions of which have served so many generations of soil students and scientists, will continue to help future generations of soil scientists to benefit from a global ecological view of soils.
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Thoroughly updated and now in full color, the 15th edition of this market leading text brings the exciting field of soils to life. Explore this new edition to find: A comprehensive approach to soils with a focus on six major ecological roles of soil including growth of plants, climate change, recycling function, biodiversity, water, and soil properties and behavior. New full-color illustrations and the use of color throughout the text highlights the new and refined figures and illustrations to help make the study of soils more efficient, engaging, and relevant. Updated with the latest advances, concepts, and applications including hundreds of key references. New coverage of cutting edge soil science. Examples include coverage of the pedosphere concept, new insights into humus and soil carbon accumulation, subaqueous soils, soil effects on human health, principles and practice of organic farming, urban and human engineered soils, new understandings of the nitrogen cycle, water-saving irrigation techniques, hydraulic redistribution, soil food-web ecology, disease suppressive soils, soil microbial genomics, soil interactions with global climate change, digital soil maps, and many others Applications boxes and case study vignettes bring important soils topics to life. Examples include “Subaqueous Soils—Underwater Pedogenesis,” “Practical Applications of Unsaturated Water Flow in Contrasting Layers,” “Soil Microbiology in the Molecular Age,” and "Where have All the Humics Gone?” Calculations and practical numerical problems boxes help students explore and understand detailed calculations and practical numerical problems. Examples include “Calculating Lime Needs Based on pH Buffering,” “Leaching Requirement for Saline Soils,” "Toward a Global Soil Information System,” “Calculation of Nitrogen Mineralization,” and “Calculation of Percent Pore Space in Soils.”
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The effects of farmyard manure (FYM), Tithonia diversifolia (tithonia) and urea when applied alone or in combination with Minjingu phosphate rock (MPR), Busumbu phosphate rock (BPR) or triple superphosphate (TSP) on soil acidity, P availability, maize yields and financial benefits were evaluated at Bukura and Kakamega in western Kenya. A reduction in exchangeable acidity and Al was observed in most tithonia- and FYM-treated soils, but not with inorganic P sources when applied in combination with urea. The effectiveness in increasing available soil P followed the order; TSP > MPR > BPR among inorganic P sources, and FYM > tithonia among organic materials at both sites. At Bukura, a site higher in both available P and Al saturation compared with Kakamega, maize did not respond to inorganic P sources applied in combination with urea. Maize, however, responded when inorganic P sources were applied in combination with FYM or tithonia at this site. At Kakamega, maize responded to TSP but not to MPR or BPR when applied with urea. Application of TSP in combination with tithonia gave the highest maize yields at both sites. Of the tested technologies, only FYM when applied alone at Bukura was economically attractive.
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Maize (Zea mays L.) is one of the world’s most important cereals and is a staple food for many people in developing countries. However, in acid soils (pH < 5.5), its productivity is limited by aluminium (Al) toxicity, besides other factors. The objectives of this study were to: develop Al tolerant maize inbred lines for a maize breeding program in Kenya, develop single cross hybrids (SCHs) from some of the tolerant inbred lines and determine Al tolerance levels of the SCHs. One hundred and seventy five inbreds and 49 SCHs were developed and screened in nutrient culture containing 0 or 222 μM using Relative Net Root Growth (RNRG), hematoxylin staining (HS) and under Al saturated field conditions (44%-45.6%) at Sega and Chepkoilel. Seedling root growth was inhibited in 95% of the inbreds. F1 hybrids obtained from inbreds varying in Al tolerance, exhibited tolerance equal to or greater than that of the more tolerant parent indicating a positive transgressive inheritance to Al toxicity. Fifty eight percent of the F1 SCHs were heterotic for tolerance to Al toxicity. Al tolerance estimated by RNRG was well correlated to that of HS (r2 = 0.88, P < 0.005) but minimally correlated with the field estimates (r2 = 0.24-0.35), implying that RNRG can predict field selection under Al toxic soils by between 24% and 35%. Plant breeders should therefore employ both approaches in selecting cultivars under Al stress. This study has developed and identified Al tolerant inbreds and SCHs for use in the acid soils of Kenya and similar regions.
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In Kenya, maize (Zea mays L.) is mainly grown on acid soils in high rainfall areas. These soils are known for low available phosphorus (P), partly due to its sorption by aluminium (Al) and iron oxides. The study determined soil P sorption, lime requirements and the effects of lime on soil pH, Al levels and available P on the main maize growing acids soils in the highlands east and west of Rift Valley (RV), Kenya. Burnt lime containing 21% calcium oxide was used. The soils were strongly to extremely acid (pH 4.85-4.07), had high exchangeable Al3+ (> 2 cmol Al kg-1) and Al saturation (> 20% Al), which most maize germplasm grown in Kenya are sensitive to. The base cations, cation exchange capacity and available P (< 10 mg P kg-1 bicarbonate extractable P) were low, except at one site in the highlands east of RV indicative with history of high fertilizer applications. Highlands east of RV soils had higher P sorption (343-402 mg P kg-1) than the west (107-258 mg P kg-1), probably because of their high Al3+ ions and also the energies of bonding between the soil colloids and phosphate ions. Highlands east of RV also had higher lime requirements (11.4-21.9 tons lime ha-1) than the west (5.3-9.8 tons lime ha-1). Due to differences in soil acidity, Al levels and P sorption capacities within and between highlands east and west of RV, blanket P fertilizer and lime recommendations may not serve all soils equally well.
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The Chaobai watershed in northern China is the most important source of drinking water for Beijing. The level of fertilizer use, especially overuse, as well as farming practices in the region have a great impact on the water quality downstream and affect an enormous number of people. This study analyzes the factors influencing the farmers' decisions on fertilizer use and the implications for water quality. The analysis is based on a survey of 349 farm households. It takes into consideration both farm and farmer specific characteristics and farmers' subjective evaluations of factors shaping their decisions. Regression models are used to examine the determinants of fertilizer use intensity across farm households and to investigate the factors influencing the overuse of nitrogen. The results suggest that many of these subjective factors have great significance in determining famers' decisions. The results also show that irrigation, gains in crop yield and higher earning goals are positively correlated with fertilizer use intensity, while farm size, manure application, soil fertility and the distance to fertilizer markets are negatively correlated. Investigation of the overuse problem shows that higher education level significantly reduces the probability of over-fertilization. Based on these findings a few policy relevant implications are discussed.
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Low soil fertility is one of the most important biophysical constraints to increasing agricultural productivity in sub-Saharan Africa. Several renewable soil fertility replenishment (RSFR) technologies that are based on nutrient re-cycling principles have been developed in southern Africa. Some success stories have been recorded (e.g. nitrogen-fixing legumes), but the adoption of RSFR technologies has generally lagged behind scientific advances thereby reducing the potential impacts of the technologies. This paper describes the major RSFR technologies being promoted in the region, synthesizes available information regarding their adoption by farmers, and identifies the challenges, key lessons learnt and the way forward for up-scaling RSFR technologies in the region. The review indicated that farmer uptake of RSFR technologies depends on several factors that can be grouped into broad categories: technology-specific (e.g. soil type, management regime), household-specific (e.g. farmer perceptions, resource endowment, household size), policy and institutions context within which RSFR is disseminated (inputs and output prices, land tenure and property rights), and geo-spatial (performance of species across different bio-physical conditions, location of village). Adoption of RSFR technologies can be enhanced by targeting them to their biophysical and social niches, facilitating appropriate policy and institutional contexts for dissemination, understanding the broader context and dynamics of the adoption process, a paradigm shift in the approach to the dissemination of RSFR (e.g. expanding RSFR to high value crop systems, exploring synergy with inorganic fertilizer) and, targeted incentive systems that encourage farmers to take cognizance of natural resource implications when making agricultural production decisions.
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Phosphorus and nitrogen deficiencies limit production of maize ( Zea mays L.) in many soils of western Kenya. Considerable amount of work has been done on N nutrition of maize in the region. There is, however, paucity of information on which to base fertiliser P recommendations for increased maize production considering potential differences in responses due to varieties, soil type, and climate. External and internal P requirements, and P utilisation efficiencies of two open pollinated varieties (Ababari and Oking') and one hybrid (H513) were examined at four P-deficient on-farm sites (2 Ferric Alisol, 1 Haplic Ferralsol, and 1Ferric Acrisol) in western Kenya. The varieties were grown under P fertilisation rates of 13, 26, 39, 52 kg P ha-1 and a check (no P application). Maize performance varied with site, rate of P application, and variety. The highest grain yields (15% moisture content) at the sites varied from 2,732 to 6,479 kg ha-1 for Ababari, 2,350 to 5,835 kg ha-1 for H513, and 2,299 to 4,459 kg ha-1 for Oking'. Internal P requirements ranged from 7 to 24 kg P ha-1 for Ababari, 4 to 18 kg P ha-1 for Oking', and 5 to 18 kg P ha-1 for H513. Internal P requirements depended on both variety and environment, but more on environment than on variety. Phosphorus physiological efficiency (kg grain kg-1 P) ranged from 111 to 314 for Ababari, 145 to 277 for Oking', and 127 to 390 for H513. Ababari performed as well as did H513, and the two were better than Oking'. Ababari is, therefore, recommended for the region since it is open pollinated and, hence, the peasant farmers do not have to buy the seeds every season. Row application of P is inappropriate in case determination of crop external P requirement is required.
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The U.S. Department of Agriculture Area Studies Project was designed to characterize the extent of adoption of nutrient, pest, soil, and water management practices and to assess the factors that affect adoption for a wide range of management strategies across different natural resource regions. The project entailed the administration of a detailed field-level survey to farmers in 12 watersheds in the Nation to gather data on agricultural practices, input use, and natural resource characteristics associated with farming activities. The data were analyzed by the Economic Research Service using a consistent methodological approach with the full set of data to study the constraints associated with the adoption of micronutrients, N-testing, split nitrogen applications, green manure, biological pest controls, pest-resistant varieties, crop rotations, pheromones, scouting, conservation tillage, contour farming, strip cropping, grassed waterways, and irrigation. In addition to the combined-areas analyses, selected areas were chosen for analysis to illustrate the difference in results between aggregate and area-specific models. The unique sample design for the survey was used to explore the importance of field-level natural resource data for evaluating adoption at both the aggregate and watershed levels. Further analyses of the data illustrated how the adoption of specific management practices affects chemical use and crop yields.
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Farmers' perception of the environmental impacts of modern agricultural technology diffusion and factors determining such awareness were examined using survey data from 21 villages in three agro-ecological regions of Bangladesh. Results reveal that farmers are well aware of the adverse environmental impacts of modern agricultural technology, although their awareness remains confined within visible impacts such as soil fertility, fish catches, and health effects. Their perception of intangible impacts such as, toxicity in water and soils is weak. Level and duration of modern agricultural technology adoption directly influence awareness of its adverse effects. Education and extension contacts also play an important role in raising awareness. Awareness is higher among farmers in developed regions, fertile locations and those with access to off-farm income sources. Promotion of education and strengthening extension services will boost farmers' environmental awareness. Infrastructure development and measures to replenish depleting soil fertility will also play a positive role in raising awareness.
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The objective of this study was to determine factors influencing the rate and intensity of adoption of poultry technology, assuming the two decisions process were separate. The double-hurdle class of model has been applied in this paper with this important distinction in mind. The model was fitted to a sample of 200 smallholder farmers from east Shewa and Welayeta zones in Ethiopia. Results indicate that 41.5% of the study farmers reported adoption of exotic poultry with a mean proportion of 0.54. As expected, there were different sets of factors behind the decision to adopt and the decision about to which extent to do so. Farmers' decision on adoption of poultry technology was positively affected by sex of the household head, family size, availability of supplementary feed, credit and extension service and extent of expected benefit from poultry, and negatively affected by market problem. On the other hand, farmers' decision on the extent of adoption of exotic poultry breed was positively influenced by age of the household head, experience in adoption of poultry technology, expected benefit from poultry and negatively influenced by market problem.
Article
The effect of incorporation of lupine and garden pea on selected soil chemical properties and growth of weeds in a potato cropping system was evaluated in North Rift, Kenya. The study was carried out in a well drained, extremely deep, dusky red to dark reddish brown, friable clay, acid humic top soil. Two weeding regimes (at legume incorporation stage and/or at 50% potato flowering stage), three nitrogen levels (0, 60 and 120 kg N ha-1) applied as CAN and two legumes plus a control (garden pea, lupine and none) were evaluated in a split-split plot design with weeding regimes as the main plots, N as sub-plots and legumes as the unit plots. Incorporation of legumes significantly (p < 0.05) raised soil pH from 3.6 - 3.9 and to 4.2; increased soil available P from 15 mg/kg to 25 and to 29 mg/kg for garden pea and lupine, respectively. The two legumes interacted with weeding regime and N reducing sheep sorrel weed density and biomass. The significantly higher lupine effects were attributed to its high biomass production suggesting that legumes may best improve soil fertility and reduce soil acidity when incorporated in the soil as green manure.
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This paper presents a dynamic model of diffusion of a new technology involving a variable input. The model highlights the role of active information accumulation, which entails costs. It generates several hypotheses regarding the likely pattern of adoption and use of the variable input over time by farmers of differing holding sizes and different access to information. It provides a possible explanation to the often observed lag in adoption of innovations by smaller farmers. Analysis of data from India on knowledge and adoption of several practices yields results which are generally consistent with the hypotheses suggested by the theoretical framework.
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The study investigated the adoption and perception of farmers in Akinyele Local Government of Oyo State, Nigeria of technologies developed by International Institute of Tropical Agriculture (IITA). Socio-economic characteristics of the respondents and their relationships with the adoption of technologies were also determined. Survey data from 200 farmers in four purposively selected villages were used. Findings revealed that the on-farm trials by IITA scientists with farmers in the local government influenced the adoption of some the technologies. The improved cassava and maize varieties, rapid multiplication of cassava and seed yam minisett technique had the highest adoption. Non-adoption of some technologies was attributed to inadequate information and missing knowledge, lack of awareness of the technologies and lack of follow-up by extension staff. Level of respondents’ education, participation in on-farm trials, contact with extension staff and years of farming had significant relationships with adoption. The study therefore recommended intensification of adequate and effective research – extension - farmer linkages and possible establishment of extension liaison services by international agricultural research centers for easy and better dissemination of their research findings.
Article
Aluminum (Al) tolerant and sensitive plants selected from the tropical maize variety Taiúba were grown in complete nutrient and simple salt solutions in the presence and absence of phytotoxic concentrations of Al. During the first 20 hr of Al exposure, the root growth rate of both tolerant and sensitive plants was severely inhibited as a consequence of Al infiltration into the root tip cells. After this period, however, roots of Al-treated tolerant plants recovered to a growth rate similar to that of control plants, while the root growth rate of sensitive plants remained severely inhibited. The recovery of the root growth rate of tolerant plants coincided with the extrusion of the Al that had been absorbed in the first 20 hr of Al exposure. When the roots of tolerant and sensitive plants were grown in simple salt solutions containing a series of Al concentrations, a dose-dependent citrate and malate exudation was observed from tolerant but not from sensitive roots. The level of citrate exudation was two- to four-fold that observed for malate. The organic acid exudation was not influenced by the level of phosphate in the growth solution, suggesting a specific Al-inducing process involved in the Al tolerance in maize. We concluded from these results that the Al infiltration in the roots at the beginning of Al exposure induces the exudation of organic acids which may exclude the toxic ion from the root tip cells of tolerant plants.
Article
In Kenya, 70 long-term fertilizer trials were established in which the response of the major annual crops to nitrogen, phosphorus and farmyard manure was tested. As the sites all represent well-defined agro-ecological units, the trial results can be used as a basis for area-specific fertilizer recommendations. Results of 4 years (1987–1990) of fertilizer and manure application to maize at three sites were evaluated. The selected sites are at altitudes of 2020 m (Nitisol), 1160 m (Phaeozem), and 130 m (Alisol). All the sites are in maize-growing environments, but farmers use different hybrids. Analysis of variance revealed that maize on the Nitisol responded vigorously to phosphorus and manure, with even a significant interaction. On the Phaeozem, it was solely nitrogen that limited yields, and on the Alisol there was a response to both nitrogen and phosphorus. At a relatively low level of fertilizer input (Sh. 825–1125), farmers can, in 3 out 4 years, earn an extra Sh. 3000 from the Nitisol (value/cost 4.5), Sh. 4000 from the Phaeozem (value/cost 4.2), but only Sh. 425 from the Alisol (value/cost 1.5). The study clearly shows the need to (i) recommend fertilizers according to the agro-ecological diversity of agricultural land, and (ii) support systems of integrated nutrient management, particularly in areas of low soil fertility, where the farmer has too few economic incentives to rely solely on mineral fertilizers.
Article
Many soils in the highlands of East and Central Africa are depleted of soil nutrients, particularly P. Our objective was to compare cattle manure, Calliandra calothyrsus Meissner leaf biomass, and triple superphosphate (TSP) as sources of P for maize (Zea mays L.), both individually and as mixtures of organic (manure or calliandra) and inorganic (TSP + urea) sources. Field experiments were conducted on a Kandiudalf at two sites in western Kenya. Net benefits were computed as the difference between the value of additional maize yield accruing from nutrient inputs and the associated additional costs. Maize grain yield was 0.6 Mg ha-1 for application of urea without P. Application of 10 kg P ha-1 as organic, inorganic, and mixtures of organic and inorganic sources significantly increased maize yield. Grain yield for manure at least equaled and sometimes exceeded (P≤ 0.05) yield for calliandra and TSP + urea. Net benefits in U.S. dollars (USD) for two seasons were highest for manure spot placed in the planting hole (293 USD ha-1), broadcast manure (255 USD ha-1), and broadcast TSP + 44 kg urea-N ha-1 (313 USD ha-1 at P = 30 kg ha-1 and 98 USD ha-1 at P = 10 kg ha-1). Net benefits for calliandra leaf biomass were highest (136 USD ha-1), when biomass was valued at cost of production and integrated with TSP, such that it provided all the N for maize and TSP provided the additional P not supplied by calliandra. Calliandra valued at its opportunity cost as a protein supplement for dairy cattle was not an economic source of P. Sensitivity analyses suggest that organic materials most suitable for use as P sources have high P content and low cost of production.
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