Soil Fertility Management Options Research Articles

Modeling the effect of soil fertility management options on maize yield stability under variable climate in a sub-humid zone in Ghana

IntroductionUncertainty in the yield of maize due to variability in weather is a major challenge to smallholder farmers in Sub Sahara Africa. This study explores the potential of combining locally available organic resources and inorganic fertilizer to increase grain yield and reduce variability in yields associated with variations in rainfall distribution.MethodsTo assess the effectiveness of this practice, the Agricultural Production Systems sIMulator (APSIM) crop model was calibrated and evaluated using maize experiments on nutrient management options. The evaluated model was used to simulate maize growth and yield using multiple-year data (1984–2018) under different planting windows for two growing seasons. The treatments were (i) control, (ii) inorganic fertilizer alone (INOFRecom), combining organic resources [empty fruit bunch of palm (EFB) and compost with inorganic fertilizer (INOF) to make up equivalent nutrients in (ii)]; (iii) EFB + INOF and (iv) Comp + INOF.ResultsThough all the soil amendments boosted grain output, the EFB + INOF treatment outperformed the other treatments in the major season with gains of between 161 and 211% and the most stable (least inter-annual variability of 27%) yield. Across the planting windows, the INOFRecom and EFB + INOF treatments achieved comparable yield increments in the minor season. Though grain yield variability was high during the minor rainy season, combining organic and inorganic fertilizers reduced inter-annual yield variability, thus, lowering uncertainty in yield due to variable inter-annual rainfall. Combining local organic resources with a reduced amount of inorganic fertilizer produced higher yields and better yield stability compared to using only inorganic fertilizer.DiscussionsThus, such soil fertility management solutions might sustain resource use and boost maize grain yield in the study area, where strategies for sustainable crop nutrition remain a critical necessity. The improved nitrogen management regimes may result in fewer environmental hazards for vulnerable rainfed agricultural systems.

Diversity of soil fertility management options in maize-based farming systems in northern Benin: A quantitative survey

Introduction: Maize-based production systems in Sub-Saharan Africa are largely based on family farming, which is characterized by low-input, nutrient-mining agriculture and practices. These systems usually promote soil degradation through loss of organic matter and erosion. The present study characterizes farms and main soil fertility management options in maize-based farming systems of the northern Benin.Methods: The study was conducted in the municipalities of Malanville, Banikoara and Bembèrèkè. We sampled randomly and interviewed 262 maize farmers, and the statistical analysis (distribution of means and frequencies, chi-square, ANOVA, etc.) was performed.Results and discussion: The results show that maize farming characteristics and socioeconomic conditions (land use and labor, production activities and land allocation, institutional arrangements on land, access to labor and capital, etc.) were diverse across locations and exhibited a wide variation within locations. Several practices were used for the management and sustainable maintenance of soil fertility in maize production systems in northern Benin: maize-legume intercropping, cotton-maize rotation, and mineral and organic fertilizers application. Most of farmers occasionally or regularly used mineral fertilizers (95.4%), followed by legume-cereal rotation/ intercropping (51.9%). Overall, 23.6% and 58.4% of farmers consistently used mineral fertilizer over the last 5 and 10 years, respectively. The amount of applied mineral fertilizer did not significantly vary between locations with an average (applied day after sowing, DAS) of 131.7 ± 13.7 (22 ± 8 DAS), 58.7 ± 9.6 (44 ± 5 DAS) and 164.7 ± 25.4 (38 ± 11 DAS) kg ha−1 for NPK, urea and Mix NPK + urea, respectively applied at, and days after sowing. Most farmers spread the fertilizer around the plants without covering with soil particles. Manure was applied exclusively to food crops through transporting and corralling (28.2%); and most farmers also used manure from their own livestock while few farmers used cattle corralling. Farmyard manure was mainly spread (100% of respondents) on the surface before plowing at the beginning of the rainy season. Maize farmers applied mineral fertilizer based on the level of initial soil fertility (naturally fertile or poor, degree of erosion etc.) and fertilizer purchase costs. Manure was not widely used as an alternative to chemical fertilizers; therefore, farmers need more strengthening and technical assistance on the production of organic fertilizers and manure storage. The findings are useful for policymakers on encouraging the successful implementation of sustainable soil fertility management strategies of maize-based farming systems in northern Benin.

Combined Agronomic and Economic Modeling in Farmers’ Determinants of Soil Fertility Management Practices: Case Study from the Semi-Arid Ethiopian Rift Valley

Studies on smallholders’ determinants of soil fertility management practices have become increasingly important for boosting agricultural productivity, particularly in cereal-based farming systems in sub-Saharan Africa. In these parts of Africa, farmers preferentially apply organic and inorganic fertilizers to the fields close to their housing compounds (infields). In addition, they prefer to use more fertilizers to grow cash crops rather than food crops. Many researchers suggested that farmers use limited nutrient resources in their hot-spot fields, e.g., infields and/or cash-crop fields. Recent econometric case studies have suggested using a model that considers a complementarity or substitutability between organic and inorganic fertilizers use. This study employed bivariate probit models to analyze 524 plot data collected from the northern semi-arid Ethiopian Rift Valley. A K-means cluster analysis divided the sample data into two subdatasets, representing food-crop-based cropping system (FCCS) and cash-crop-based cropping system (CCCS). Based on narrative inquiry interviews and the cluster analysis, this study considered reflecting the structure of the local farming system in modeling: a data segmentation approach and dummy variable method. Bivariate and univariate probit analyses showed that, first, the farmers’ determinants differed between the FCCS and CCCS. Second, the correlation between organic and inorganic fertilizers use was independent. Farmers’ determinants were primarily governed by the biophysical features of the plots (commuting distance to the plot, plot size, type of the plot, etc.), which narrowed down the feasible soil fertility management options in the plot to one or two; farmers’ more specific decisions on soil fertility management practices depend on individual farmers’ socioeconomic endowments (farm holding, livestock ownership, etc.).

Effect of combining organic manure and inorganic fertilisers on maize–bush bean intercropping

SummaryIn sub-Saharan Africa (SSA), farmers intercrop common beans with maize but apply inorganic or organic fertilisers targeting only maize. Effects of this practice on bush bean yield have not been fully evaluated with respect to input use and compatibility when intercropped with maize. An on-farm trial managed by smallholder community members was conducted to assess the influence of various soil fertility management options and cropping systems on the yield of two bush bean genotypes (SER45 and SER83) in two agro-ecological zones of Malawi. The farmer-managed trials were laid out in split-plot design, with the bean genotypes as main plots and a combination of the soil fertility management options (i.e., no input, manure, fertiliser and fertiliser + manure) and cropping systems (i.e., sole crop and intercrop) as subplots. The trials were affected by terminal drought and dry spells, but results show that manure and fertiliser application enhanced the resilience of the drought-tolerant bean genotypes. The genotype SER45 was responsive to manure application in the sole crop, giving a 44.4% yield increase over no-manure application. In sole cropping with fertiliser plus manure, bean yields improved by 40.1% for SER45 and 78.3% for SER83 relative to the no-input control. Although sole cropping had higher bean yields, the treatment with manure and fertiliser had a higher land equivalence ratio for intercrop of 1.54 for SER45 and 1.32 for SER83 over sole cropping. These results show that, under smallholder farmer management, the climate adaptability of bush bean genotypes could be enhanced by the combined application of organic and inorganic fertilisers in maize–bean intercrop. The combined application also enhances whole-farm productivity of the common maize–bean intercrop practice than monocrop, hence is of benefit to most low-input smallholder farmers of SSA.

Understanding factors influencing wheat productivity in Ethiopian highlands

Summary Increasing yields in farmer fields is a priority to address increasing food demands. The study was conducted within four wheat-growing areas in Ethiopia: Debre Birhan, Hosaina, Sinana and Maychew. The objectives were to identify (1) best-bet soil fertility management options based on agronomic performance and economic evaluation and (2) key yield-reducing factors in farmer fields based on an agronomic survey among 55 participating farmers. Two types of on-farm experiments were conducted: researcher-managed trials that tested combinations of nutrients, including micronutrients, organic resources or both over two cropping seasons and farmer-managed trials comparing ‘improved practice’ against ‘farmer’s practice’. Fertilizer treatment affected wheat productivity in Debre Birhan (p < 0.01), a site limited in sulphur. Here, full NPK increased yields over the control (p < 0.05), whereas a combination of NPK and manure was better than the application of manure as the only source of added nutrients (p < 0.05). Applying half the recommended NPK with micronutrients and manure achieved similar yields as the full fertilizer treatment. In Hosaina, treatment had no significant effect on wheat productivity, although a combination of NPK and zinc resulted in an additional 26–57% yield relative to the other treatments. In Maychew, a significant treatment effect (p < 0.05) was observed. Here, the treatment with lower rates of nitrogen and phosphorous had lower yields than the full NPK treatment. A significant effect of plant densities on on-farm productivity was also observed. We conclude that although nutrient management including use of micronutrients is important in specific cases, investments to optimize plant densities have a huge potential to increase food productivity.

Good soil management can reduce dietary zinc deficiency in Zimbabwe

BackgroundDietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of surveys and field experiments.MethodsAn ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios.ResultsA baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg−1 and an estimated dietary Zn intake of 9.3 mg capita−1 day−1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and woodland leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg−1. This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2238 DALYs year−1. Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg−1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9119 DALYs year−1. Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods.ConclusionFarmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

English

Synthetic fertilizers and pesticides in vegetable production have negatively impacted the soils, water quality, food security and health of farmers and consumers. Hence, sustainable, economically feasible, environmentally friendly soil fertility, pests and disease management options are needed to improve vegetable production. This study evaluated the growth and yield of okra due to varying rates of different sources of organic soil amendments to promote its productivity and tolerance in Sierra Leone. A randomized complete block design (RCBD) with three (3) replicates and ten (10) treatments was used. The treatments included; Gliricidia sepium, chicken manure and cow dung applied as sole treatments and in combination with papaya leaf and neem leaf as biopesticides. Data was collected on the growth, yield and percentage leaf damage of okra. Analysis of Variance (ANOVA) showed significant differences in treatment means. The application of poultry manure in combination with papaya leaf gave the most satisfactory performance in all parameters compared to chicken manure, G. sepium, and cow dung in sole application, and their combined applications with paw-paw leaf and neem leaf. Incidence of pest (Podagrica spp) was minimal with the application of poultry manure in combination with papaya leaf, resulting in less severity leaf damage on okra. Key words: Okra, Organic, Biopesticides, Pest, Productivity, Tolerance.

Improvement of sorghum productivity through introducing integrated soil fertility management options in the Northern Sudanian zone of Burkina Faso

Agricultural intensification is a necessity to ensure food security in the Sahel countries. This study aimed at assessing the effects of technological packages of integrated soil fertility management on sorghum productivity. An experiment was set up in dispersed blocks design where each producer constituted a repetition. Fertilizers were applied using the microdose technique. The results showed that the best grain yields of sorghum are obtained with the technology combining stone bunds + zaï + NPK + urea with respectively 1428.70 kg / ha in 2018 and 1158.40 kg / ha in 2019. The grain yield gaps between the current farmers’ practice under stone bunds and ISFM packages varied from 5.66% to 44.45% in 2018 and from 25.15% to 53.80% in 2019. In the context of climate variability and climate change, these results show that water harvesting techniques such as stone bunds and the zaï, associated with microdose are viable and sustainable alternative for improving agricultural productivity.
 L’intensification agricole est une nécessité pour assurer la sécurité alimentaire dans les pays du sahel. Cette étude avait pour objectif d’évaluer les effets de paquets technologiques de gestion intégrée de la fertilité des sols sur la productivité du sorgho. Pour ce faire, un dispositif en blocs dispersés a été mis en place en milieu paysan où chaque producteur constituait une répétition. Les paquets technologiques se composent des formules de fumures et/ou des techniques de conservation des eaux et des sols (CES). Les engrais ont été apportés selon la technique de la microdose. Les résultats ont montré que les meilleurs rendements grains du sorgho ont été obtenus avec la technologie cordons pierreux + zaï + NPK + urée avec respectivement 1428,70 kg/ha en 2018 et 1158,40 kg/ha en 2019. Les gaps de rendement grains entre la pratique actuelle des producteurs sous cordons pierreux et les paquets technologiques ont varié de 5,66% à 44,45% en 2018 et de 25,15% à 53,80% en 2019. Dans le contexte de la variabilité et des changements climatiques, ces résultats montrent que la collecte et la valorisation de l’eau à la parcelle à travers les cordons pierreux et le zaï, associée à la microdose est une alternative viable et durable d’amélioration de la productivité agricole.

Integrated Soil Fertility Management Options for Maize Production and Sustainability in the Western Highlands of Cameroon

Background: Continuous cultivation without fertilizer application and soil erosion are responsible for plant nutrient depletion and yield decline of major food crops in Sub-Saharan Africa.Methods: Nutrient status of Calliandra calothyrsus, Leucaena leucocephala, Acacia angustissima and Cassia spectabilis were characterized. Field experiments were conducted over two years in the Western Highlands of Cameroon to evaluate the effects of the application of leaf biomass of agroforestry tree species and mineral fertilizers on maize yield performance. The residual effects on soil physicochemical properties were also investigated for umbric Cambisols of Babungo and ustic Oxisols of Bansoa. Ten treatments encompassing; sole leaf biomass of Calliandra calothyrsus, Leucaena leucocephala, Acacia angustissima and Cassia spectabilis, leaf biomasses combined with NPK fertilizer, sole NPK fertilizer and absolute control were laid in a randomized complete block design and replicated three times. Data were subjected to analysis of variance and the Duncan Test (p < 0.05) used for mean separation.Results: All the species characterized had nitrogen, polyphenol and lignin contents greater than 2.5 %, 5 % and 15 % respectively. Significant differences (p < 0.05) were observed among treatments on maize growth, productivity parameters and soil chemical properties for both soil types. The highest maize grain yields were recorded in plots amended with 1 t/ha of biomass of Calliandra calothyrsus or Leucaena leucocephala as well as1.5 t/ha of biomass of Acacia angustissima and Cassia spectabilis plus mineral fertilizer (50 N+ 37.5 P2O5 + 45 K2O) on both soils compared to other treatments.on umbric Cambisols and ustic Oxisols respectively. The residual effects of treatments on soil chemical properties showed severe nutrient depletion in control plots and those amended with sole inorganic fertilizer.Conclusions: Combined application of agroforestry tree biomass and inorganic fertilizers remains an appropriate technology to enhance maize yield and sustain production of resource-limited farmers of acid tropical soils..

Agro‐ecology, resource endowment and indigenous knowledge interactions modulate soil fertility in mixed farming systems in Central and Western Ethiopia

AbstractSite‐specific soil fertility management requires a fundamental understanding of factors that modulate soil fertility variability in the local context. To verify this assumption, this study hypothesized that soil fertility variability across two regions in Central and Western Ethiopia is determined by inter‐related effects of agro‐ecological zones and farmers’ resource endowment (‘wealthy’ versus ‘poor’ farmers). Mid‐infrared spectroscopy coupled to partial least squares regression (midDRIFTS‐PLSR) and wet‐laboratory analyses were used to assess the soil fertility (soil pH, total soil carbon [TC] and nitrogen [TN], plant‐available phosphorous [Pav] and potassium [Kav]) across four agro‐ecological zones: ‘High‐Dega’ (HD), ‘Dega’ (D), ‘Weina‐Dega’ (WD) and ‘Kola’ (K). MidDRIFTS peak area analysis of spectral frequencies (2,930 [aliphatic C‐H], 1,620 [aromatic C = C], 1,159 [C‐O poly‐alcoholic and ether groups] cm‐1) was applied to characterize soil organic carbon (SOC) quality and to calculate the SOC stability index (1,620:2,930). Higher TC in HD, as well as higher TN and Kav contents in K were found in fields of wealthy compared with poor farmers. Resource endowment dependent soil fertility management options revealed SOC of higher quality in wealthy compared with poor farms in D. Agro‐ecological zones distinctions contributed to these soil fertility differences. Farmers distinguished visually fertile and less fertile fields based on soil colour. Higher pH in K and WD as well as Pav in K and HD were found in fertile (brown/black) than less fertile (red) soils. To conclude, tailor‐made soil fertility management in the local context must consider agro‐ecological zones and resource endowment interactions along with farmers’ indigenous knowledge.

Good soil management can reduce dietary zinc deficiency in Zimbabwe.

Abstract Dietary zinc (Zn) deficiency is widespread in sub-Saharan Africa (SSA) with adverse impacts on human health. Agronomic biofortification with Zn fertilizers and improved soil fertility management, using mineral and organic nutrient resources, has previously been shown to increase Zn concentration of staple grain crops, including maize. Here, we show the potential of different soil fertility management options on maize crops to reduce dietary Zn deficiency in Zimbabwe using secondary data from a set of survey and field experiments. An ex-ante approach was used, informed by published evidence from studies in three contrasting smallholder production systems in Zimbabwe. To estimate current Zn deficiency in Zimbabwe, data on dietary Zn supply from non-maize sources from the Global Expanded Nutrient Supply (GENuS) data set were linked to maize grain Zn composition observed under typical current soil fertility management scenarios. A baseline dietary Zn deficiency prevalence of 68% was estimated from a reference maize grain Zn composition value of 16.6 mg kg -1 and an estimated dietary Zn intake of 9.3 mg capita -1 day -1 from all food sources. The potential health benefits of reducing Zn deficiency using different soil fertility management scenarios were quantified within a Disability Adjusted Life Years (DALYs) framework. A scenario using optimal mineral NPK fertilizers and locally available organic nutrient resources (i.e. cattle manure and leaf litter), but without additional soil Zn fertilizer applications, is estimated to increase maize grain Zn concentration to 19.3 mg kg -1 . This would reduce the estimated prevalence of dietary Zn deficiency to 55%, potentially saving 2,238 DALYs year -1 . Universal adoption of optimal fertilizers, to include soil Zn applications and locally available organic leaf litter, is estimated to increase maize grain Zn concentration to 32.4 mg kg -1 and reduce dietary Zn deficiency to 16.7%, potentially saving 9,119 DALYs year -1 . Potential monetized yield gains from adopting improved soil fertility management range from 49- to 158-fold larger than the potential reduction in DALYs, if the latter are monetized using standard methods. Farmers should be incentivized to adopt improved soil fertility management to improve both crop yield and quality.

English

This study was implemented to evaluate the performance of biofortified bean under different integrated soil fertility management (ISFM) options and agro-ecological conditions in Democratic Republic of Congo (DRC). A Split-plot design with eight genotypes as main factors and four ISFM options as secondary factors was carried out in eight production zones distributed across South-Kivu, North-Kivu, and Katanga provinces. The application of lime + manure + NPK increased the bean yield by 173% in Lohutu. Compared to local variety in Lohutu, the CODMLB001 variety under the same option increased the yield by 252%. The same ISFM option allowed best response in terms of micronutrient content of bean in Rutshuru, inducing up to 80.3 mg.kg-1 Fe, representing increase 41%. For Zn, the best response was obtained with lime + NPK applied in Kipopo that induced up to 32.2 mg.kg-1 Zn. Lime + manure + NPK fertilizer option reduced root rot severity by 17.8% compared to the control. This study confirmed the potential of increasing bean productivity, micronutrient  and reducing the severity of major diseases through application of  soil fertility management options, which  will vary with the bean genotype  and the environment under which bean is cultivated. Key words: Integrated soil fertility management, bean yield, micronutrient content, disease control, Phaseolus vulgaris L. &nbsp

Soil Fertility Depletion and Its Management Options under Crop Production Perspectives in Ethiopia: A Review

Soil is a non-renewable or finite resource and is the bank of nutrients for plant growth. Most soils in the tropical region including Ethiopia are highly weathered and infertile due to lower organic matter content and open nutrient cycling systems. These led to soil fertility depletion and crop productivity reduction in the country by different soil degradation agents. Therefore, the objective of this paper is to review soil fertility depletions and its management options under crop production perspectives in Ethiopia. The major drivers of soil fertility depletion are population pressure, land use pattern, free grazing of animals, lack of energy sources, land ownership and poor government policy problems. The major causes of soil fertility depletion are inadequate fertilizer use, complete removal of crop residues, continuous cropping systems, climate and soil types, lack of proper cropping systems and soil erosion and continuous cultivation. The promising technologies for improving soil fertility are integrated nutrient management, crop residue management, green manuring and cropping sequences, management of farmyard manure, applications of chemical fertilizers and soil amendments, agroforestry practices, applying conservation agriculture and application of soil-water conservation practices. Therefore, it needs a great attention by the community and the government to use innovative soil fertility management options to sustain soil fertility and crop productivity for the coming generations in the country forever enhancing nutrient input and recycling through following closed nutrient management systems in the cultivated lands.

Agricultural sustainability in context of Indian Agriculture: A parametric approach from Punjab and Haryana

An attempt was made to develop and quantify the agricultural sustainability in India, particularly in food basket states of Punjab and Haryana in the Indo-Gangetic Plains (IGP) with an improved methodological approach to capture the complexities of soil sustainability in its holistic manner. Agricultural sustainability in this study is defined in terms of soil health. Three main drivers of soil health viz. soil degradation, soil fertility and soil management options were considered to develop the sustainability index. These drivers are closely associated and defined by different soil indicators. For developing sustainability index, 15 indicators were taken by adopting various methods such as equal, principal component analysis (PCA), and expert opinion weights. Results indicated that the percentage of area under unfavourable soil structure was quite high in both Punjab (18.4%) and Haryana (27%). Similarly, the deficiency in boron (B) and soil organic carbon (SOC) in Punjab were quite high at 69.6% and 75.6%, respectively. The corresponding values of 43.2% and 90% were recorded for Haryana. Soil management practices to restore soil health were not that adequate and encouraging in these states. The percentage area under conservation agriculture (CA) is only 13.6% (Punjab) and Haryana (5.2%) as against the benchmark of 33% suggested by the experts in the field. The excess use of urea to the extent of ~70-108% from the recommended doses was recorded for Punjab and Haryana, which is real cause of concern and needs to be optimized through strong policies. The use of pesticides in agriculture (65.7% net sown area) under both states was alarming and most farmers do not use the recommended doses. Excess use of pesticide, nitrogenous fertilizers, high stubble burning and low per hectare use of farmyard manure (~0.9- 1.5 t ha-1) were found in both states. Overall, lower to moderate soil sustainability was observed in both Punjab and Haryana. By and large, PCA-based combined soil sustainability indices (CSSI) provided better results for both Punjab (0.64) and Haryana (0.60). Results highlight the importance of reorientation of the existing policies and adopting new policies, institutional arrangements and regulatory measures to enhance the degree of sustainability as measured by CSSI in both Punjab and Haryana.

Conventional versus agro-ecological intensification: assessing the effect of conservation agriculture in maize cropping systems with the DSSAT model in Côte d’Ivoire (West Africa)

Integrated soil fertility management options are being promoted as ways of adapting agricultural systems to sustain yields on highly degraded and poor soils encountered throughout West Africa. The efficiency of these practices may be affected by high variability and uncertainty associated with seasonal rainfall, especially for areas such as Cote d’Ivoire, where intra-seasonal rainfall has been observed to change from 1 year to another. The DSSAT crop simulation model was used in this study as a tool to evaluate the impacts of soil improvement options including inorganic fertilizer and conservation agriculture generating higher carbon sequestration and crop yield in maize agro-ecosystems. The model was calibrated using agronomic data for three cropping seasons from 2009 to 2010 in Goulikao (Center-West Cote d’Ivoire) and Aheremou 2 (Central Cote d’Ivoire), respectively and validated against independent datasets of yield of 2003–2004 seasons in the buffer zone of the Lamto Natural Reserve, Central Cote d’Ivoire. The model predicted average maize yields of 1454 kg ha−1 across the sites versus an observed average value of 1736 kg ha−1, R2 of 0.72, and RMSE of 597 kg ha−1 after the default values for stable soil organic matter fraction used in the model were substituted by the estimated one. For the validation, the predicted higher maize yield was consistently related to fallow biomass inputs and different rates of fertilizer, thus generating a RMSE of total aboveground biomass and grain yield of 606 kg ha−1 and 350 kg ha−1, respectively. The impact of fallow residues and cropping sequence on subsequent maize yield was simulated and compared with conventional fertilizer and control data using 12 years historic climate time series. We conclude that soil fertility improvements through conservation agriculture can sustain grain yield at the same level as conventional inputs of urea against larger climate variability. However, this system may be substituted by conventional agriculture when climate forecast reveals a dry cropping season year.

Climate change impact on water- and nitrogen-use efficiencies and yields of maize and sorghum in the northern Benin dry savanna, West Africa

Climate change and variability challenge crop productivity and resource use efficiency in West Africa. Despite abundant research on climate change impact on crop yields and food security, little is known about climate change effects on the resource use efficiencies of the main staple crops in the dry savanna agro-ecological zone of northern Benin, West Africa. This study assessed the impact of climate change on water- and N-use efficiencies, and yields of maize and sorghum in the dry savanna of northern Benin considering three soil fertility management options (return of crop residues, mineral NPK fertilizer application, and combinations of both) and three bias-corrected ensemble mean predictions (BNU-ESM, CanESM2, and MPI-ESM-MR models) of future climate (2080–2099) under Representative Concentration Pathways (RCPs) of 2.6, 4.5, and 8.5. Seasonal rainfall is projected to decrease by 2% under RCP 2.6 and by 4% under RCP 4.5, and to increase by 1% under RCP 8.5 relative to the baseline mean (1986–2005). Increasing trends in minimum temperature of +1.0 °C (RCP 2.6), +2.0 °C (RCP 4.5), +4.7 °C (RCP 8.5) and maximum temperature of +1.1 °C (RCP 2.6), +2.0 °C (RCP 4.5), +4.6 °C (RCP 8.5) are also predicted. Solar radiation was projected to decrease by about 0.4 MJ m−2 d-1. Under these projected climate scenarios, both CERES-Maize and CERES-Sorghum simulated positive responses in aboveground biomass accumulation during the vegetative growth stages. The predicted increase in aboveground biomass growth will be largest under RCP8.5 and smallest under RCP 2.6. This impact can be enhanced by improved soil fertility management, albeit with a crop-specific magnitude. Across the soil fertility management options, CERES-Maize predicted decreases in water-use efficiency by 17–53%, partial factor productivity of nitrogen (N) by 10–47%, and internal N-use efficiency by 5–33% for maize. Similarly, CERES-Sorghum simulated decreases in water-use efficiency (23–51%), partial factor productivity of N (22–49%), and internal N-use efficiency (13–47%) for sorghum. The largest overall loss in resource efficiency and yield were predicted for the RCP 8.5 scenario. The projected climate change for the dry savanna in northern Benin will likely reduce water- and N-use efficiencies as well as grain yields of maize and sorghum considerably but these results should be treated with caution due to shortcomings in the models structure for dealing with effects of enhanced CO2. For reliable assessments of climate change impact on WUE, it is critically important to update parameterization and code of the CERES crop models in DSSAT to have a sufficiently strong effect of CO2 on stomatal conductance and on transpiration.

Comparative Economic Analysis of Soil Fertility Management on Cassava Based Intercropping Systems in Oredo Local Government Area of Edo State, Nigeria

The study was carried out in Oredo Local Government Area of Edo State, Nigeria. The broad objective was to determine the comparative economic analysis of soil fertility management options on cassava based cropping/intercropping systems. Data were obtained from both primary and secondary sources, primarily data was obtained through questionnaire distributed to eighty (80) randomly sampled farmers from the study area. Economic analysis was carried out using statistical tools such as descriptive statistics which included frequency tables, percentages, means, pie charts, bar column chart etc. which was used to determine the cost and returns of both soil fertility management options. It was also necessary to test the hypothesis of the study which was tested using the Z-Test analysis due to the sample size. The result showed that higher profit was obtained from inorganic fertilizer by those farmers that made use of them in which they had a gross margin (profit) of N118, 400 when compared to those farmers that made use of organic fertilizer, having a gross margin of N60, 900. However, the result from the gross margin analysis as well as the hypothesis of the study shows that the farmers stand to gain more if they use either of the soil fertility management options on their farms. Also, considering the problem of scarcity and effect often associated with inorganic fertilizer, the choice of organic fertilizer is more likely to be accepted by the farmers. Possible recommendations were also made in the course of the study which includes, transformation of farming practices through technology that would stabilize yield and reduce unpredictable variations, farmers should be encouraged to use either of the soil fertility management options to increase their yield. Organic fertilizer should be made affordable to farmer and inorganic fertilizer should be made accessible.

Impact of Alternative Soil Fertility Management Options on Maize Productivity in Malawi’s Smallholder Farming System

This paper focuses on smallholder maize production in Malawi by investigating the link between productivity and soil fertility management. Many studies conducted in Malawi indicate declining levels of maize productivity thereby posing food security concerns, since maize is the staple crop for most areas of the country. This analysis focuses on the factors influencing productivity of maize among smallholder farmers, especially given the fears that unfavorable output and input market conditions throughout the 1990s may have compelled smallholder farmers into unsustainable agricultural intensification. Farm-household survey data is thus used to compare the productivity of smallholder maize production under integrated soil fertility (ISFM) and chemical-based soil fertility management. A normalized translog yield response model is estimated by imposing monotonicity and curvature correctness at the sample mean. The results indicate higher maize yield responses for integrated soil fertility management options, after controlling for the intensity of fertilizer application, labour intensity, seed rate, land husbandry practices and policy factors such as market access, extension and credit access. The estimated model is highly consistent with theoretical regularity conditions. Thus, the findings indicate that the use of ISFM increases maize productivity in comparison to the use of inorganic fertilizers. Since most farmers in the maize-based farming systems are crowded out of the agricultural input market and can hardly afford optimal quantities of inorganic fertilizer, enhancement of ISFM provides scope for enhancing maize productivity and food security especially where inorganic fertilizer is highly unaffordable and risky to use. Thus there is need for policy interventions to promote smallholder uptake of ISFM options. Finally areas of policy support in crop output and input market development, credit access and extension service provision are identified to enhance ISFM uptake in smallholder maize-based farming systems.

CROPGRO-Cotton model for determining climate change impacts on yield, water- and N- use efficiencies of cotton in the Dry Savanna of West Africa

Cotton is an important cash crop in many West African countries. Hence, its sustainable production will support the national economies as well as the livelihoods of the farming population alike and in turn help easing wide-spread poverty. However, future climate change may affect the productivity of cotton in West Africa. Therefore, the objectives of this study were to (i) parameterize the Cropping System Model- CROPGRO-Cotton to simulate growth, seed cotton yield, and in-season soil water dynamics and nitrogen (N) uptake, and (ii) apply the model to estimate potential climate change impacts on cotton growth, yields, and water- and N- productivity under different soil-fertility management practices. The CROPGRO-Cotton model was first parameterized and evaluated using datasets collected in three field experiments conducted in 2014 and 2015 in the Dry Savanna of northern Benin, West Africa. The model was next applied to determine long-term responses of cotton to historical (1986–2015) and projected climate (2080–2099) for three Representative Concentration Pathways (RCPs 2.6, 4.5, and 8.5). CROPGRO-Cotton accurately simulated in-season soil water dynamics (nRMSE of 12–27%, d-values of 0.79–0.88), N uptake (nRMSE of 31–44%, d-values of 0.89–0.96), and biomass accrual (nRMSE of 31–46% and d-values of 0.91–0.97), as well as seed cotton yield at harvest (nRMSE of 24–39% and d-value of about 0.81). The model predicted higher seed cotton yield with planting dates in June compared to July. Under the climate change scenario of RCP2.6, CROPGRO-Cotton predicted a decrease in water use efficiency (WUE) by 20% without any soil amendment, and by 4% with an integrated soil-crop management compared to the historical run, but an increase of 2% with a high use of mineral fertilizer. With the RCP4.5 and 8.5 scenarios, the predicted changes in WUE varied between −1% and 17% across the soil fertility management options. CROPGRO-Cotton predicted increases in N-partial factor productivity by 7 to 31%. The N uptake varied between −7% and 46% whilst seed cotton yield varied between −7 and 41%. The findings underlined that the predicted future increases in water and N productivity in cotton will be driven by CO2 fertilization, increases in temperatures as well as rainfall variability, but at the expense of soil fertility leading to soil mining. Yet, even if cotton, unlike some other crops in the region, will likely respond positively to climate change, adequate soil fertility management practices are essential to ensure efficient and sustainable water- and N- use in the expected future.

Malting barley response to integrated organic and mineral nutrient sources in Nitisol

PurposeDepletion of soil fertility accounts for the low yield and quality of malting barley (Hordeum vulgare) in Ethiopia. Mineral fertilizers can counteract nutrient depletion but are unaffordable by low-input farmers. Organic amendments can contribute to correct soil degradation but are often unavailable in the required amounts. Therefore, this experiment was conducted to investigate the effects of combined use of organic and mineral amendments on the yield and quality of malting barley, and on selected soil chemical properties at Lemu-Bilbilo district in the southeastern highlands of Ethiopia.MethodsEight treatments were arranged in randomized complete block design with three replications to compare sole and integrated applications of organic and mineral nutrient sources on crop performance attributes and selected soil characteristics.ResultsApplication of 2.82 t ha−1 compost or 1.07 t ha−1 farmyard manure (FYM) along with 18–10 kg ha−1 N–P gave 4234–4443 kg ha−1 grain yield with 15–17 and 32–39% increase over sole organic amendments and control, respectively, and 757% economic benefit. Combining organic and mineral fertilizers also gave 7–17 and 1–6% increase in available soil P and total N content of the soil.ConclusionCombined application of 50% recommended compost (RC) or 50% recommended FYM (RFYM) + 50% recommended NP (RNP) or 33% RC + 33% RFYM + 33% RNP enhanced yield, grain quality, soil attributes and economic benefits. Therefore, integration of organic and mineral amendments is recommended as best agronomic and economic optimum soil fertility management options for sustainable malting barley production in the southeastern highlands of Ethiopia.