A field study was carried out on a six-year-old on-farm field trial during long-rains season (April–August) 2003 to investigate the effect of improved fallow systems and phosphorus application on arbuscular mycorrhiza fungi (AMF) symbiosis in maize. The trial comprised of maize rotated with a fast growing leguminous Crotalaria grahamiana fallow and a non-leguminous Tithonia diversifolia fallow for 3 years followed by continuous maize. The experiment was randomized complete block design with three cropping (continuous maize, Crotalaria fallow and Tithonia fallow) systems and two phosphorus levels (0 and 50 kg P/ha). AMF colonization in maize roots, maize yield and macro-nutrients uptake were recorded. Phosphorus applications improved (P < 0.05) early (<8 weeks old maize) AMF colonization, nutrient uptake and maize yield in improved fallow systems. Greater differences due to phosphorus application were noted in maize in Tithonia fallow than in Crotalaria fallow. Following phosphorus application, a positive relationship existed between early AMF colonization and maize yield (r = 0.38), and phosphorus and nitrogen uptake (r = 0.40 and r = 0.43, respectively), demonstrating the importance of phosphorus fertilization in enhancing low-input technologies (improved fallows systems) in phosphorus deficient and acidic soils of western Kenya.
Tag: Maize
Tree species and pruning regime affect crop yield on bench terraces in SW Uganda
Integration of trees on farms may exert complementary or competitive effects on crop yield. This 4 year study examined novel systems in which Alnus acuminata (alnus), Calliandra calothyrsus (calliandra), Sesbania sesban (sesbania) or a mixture of all three were grown on the degraded upper part of bench terraces in Uganda; beans or maize were grown on the more fertile lower terrace during the short and long rains. Three pruning treatments (shoot, root or shoot root pruning) were applied to the tree rows adjacent to the crops; shoot prunings were applied as green manure to the woodlot from which they came. Pruning increased survival in calliandra and reduced survival in sesbania; alnus was unaffected. Pruning reduced tree height and stem diameter in alnus, but did not affect calliandra or sesbania. Maize yield adjacent to unpruned calliandra, alnus and sesbania or a mixture of all three was reduced by 48, 17, 6 and 24% relative to sole maize. Shoot pruning initially sustained crop performance but shoot root pruning became necessary when tree age exceeded 2 years; shoot root pruning increased maize yield by 88, 40, 11 and 31% in the calliandra, alnus, sesbania and tree mixture systems relative to unpruned trees. Bean yield adjacent to unpruned calliandra, alnus, sesbania and the tree mixture was 44, 31, 33 and 22% lower than in sole crops and pruning had no significant effect on crop yield. The results suggest that sesbania fallows may be used on the upper terrace without reducing crop yield on the lower terrace, whereas pruning of alnus is needed to sustain yield. Calliandra woodlots appear to be unsuitable as crop yield was reduced even after pruning
Agroforestry for Livelihoods of Smallholder Farmers in Northwest Vietnam – Research in Development
In Northwest Vietnam, rain-fed crop cultivation is dominated by monoculture maize,upland rice and cassava on sloping lands. The loss of topsoil during the rainy season leadsto a depletion of soil fertility and plant nutrients leading to reduction in crop yield. Farmershave to invest heavily in chemical fertilisers for the maize to remain productive comparedto the past. Harsh weather conditions also reduce yields or even lead to crop loss and makesoil and water conservation more difficult.The project has introduced trees in mono-cropped landscapes through agroforestry toreduce dependence on annual crops, as well as increase and diversifies incomes from treeproducts, while also conserving the natural resource base. The research approach combineddifferent activities, which support each other to be possible bring valuable researchresults to apply to reality. The agroforestry systems were designed through participatorywhich the scientific knowledge and local knowledge are combined. These established trialsare evaluated to find out the suitable options. The add value for agroforestry adoptionalso involved research on propagation of priority agroforestry species, small-scale nurserydevelopment, research and transfer processing techniques, exploring value-adding opportunitiesby smallholders and facilitating links between producers and other market actors.The research findings were spread through farm cross-visits, farmer field days and trainingsessions held at the test sites, accompanied by regular impact assessments. In addition,these findings were used to inform the communication strategies, policy dialogues, extensionand expansion activities through workshops, media products, extension materials andtraining. To promote the agroforestry adoption, the project has been developed at threelevels: Participatory Farmer Trials, Farmer Demonstration Trials and Exemplar Landscapeswhere the scientific knowledge and local knowledge are combined and utilised. Thisapproach is primarily based on the classic extension and dissemination theories, but highlightsthe important elements of collective action and social capital development amongfarmers, and between extension workers, local governments and researchers. The resultshave been found useful in demonstrating farmer adoption of agroforestry practices anddeveloping value chains and market linkages in varying contexts, and they support thelocal governments to define strategy development through policy interventions.
Adoption of agroforestry and the impact on household food security among farmers in Malawi
Agroforestry is increasingly regarded as an important adaptation and mitigation strategy against climate change. In particular, the use of fertilizer trees has been promoted as a practice that contributes to improved soil fertility through nitrogen fixation, by increasing supply of nutrients for crop production. While a lot of the evidence on the impact of fertilizer trees relies on on-farm experiments and correlational analysis, there is a paucity of rigorous evidence under actual smallholder farming conditions. This paper analyzes the impacts of adopting fertilizer trees such as Gliricidia sepium and Faidherbia albida on household food security. We draw on survey data of 338 farmers in Malawi and use an endogenous switching regression to rigorously analyze adoption impacts. Econometric results show that use of fertilizer tree adoption increases the value of food crops by 35%. Disaggregation of the impacts through stratification by land ownership further reveal that farmers with smaller farms of up to 2 acres realize the highest gains. Furthermore, fertilizer tree use in conjunction with improved maize seed also significantly increased value of food crops. This study offers preliminary insights that contribute to an emerging field of research on quantitative assessment of agricultural interventions such as agroforestry practices using novel analytical approaches. We provide some policy insights and recommend the need for future research to be designed around development initiatives that consider fine-scale variation in social, economic and ecological context of farmers to improve uptake and adaptation to realize the full potential of agroforestry in improving soil fertility and household food security.
Tillage and fertilizer effect on maize and soybean yields in the Guinea savanna zone of Ghana
Background: The most limiting factors for sustainable maize production in smallholder farming systems of sub-Saharan Africa, especially the savanna agro-ecological zone, are erratic rainfall pattern and low soil fertility. Methods: Research was conducted with smallholder farmers in 2013 and 2014 in two communities in the Upper West Region of Ghana to evaluate the effects of NPK mineral fertilizer (64-38-38 kg ha-1 N-P2O5-K2O, respectively) on growth and yield of maize at Bompari, and 375 kg ha-1 of YaraLegume™ fertilizer (0-18-13 NPK + 3 CaO + 2 MgO + 4 S) on growth and yield of soybean at Doggoh, under no-tillage (using pre-plant application of glyphosate) and conventional tillage (using hand hoe). Results: Mean grain yields of both maize and soybean were higher in 2014 than 2013. In both years, no-tillage and conventional tillage had similar effect on soybean plant height, pods per plant and aboveground dry matter production. Averaging over fertilizer treatment, grain yield of no-tillage soybean was 51% higher when compared with tilled soybean in 2014 only. Mean grain yield of no-tillage maize was 68% higher than that of tilled maize in 2013 only. Regardless of tillage method, fertilizer application significantly increased maize and soybean grain yields. Application of fertilizer to soybean resulted in 59% (193 kg ha-1) and 54% (474 kg ha-1) increase in grain yields in 2013 and 2014, respectively, over no fertilizer treatment. Mean grain yield of maize was 140 and 252% higher with fertilizer treatment in 2013 and 2014, respectively. No-till system showed cost savings due to reduced labour mainly for weed control. Conclusion: The results of these studies showed that no-tillage with fertilizer, whether for maize or soybean, generally resulted in the highest grain yields. No-tillage also gave the highest economic returns. Farmers can get better returns to the money invested in herbicide for producing maize and soybean under no-till than with their traditional practice even on degraded savanna soils with low levels of plant available nutrients. © 2017 The Author(s).
Unravelling the effects of soil and crop management on maize productivity in smallholder agricultural systems of western Kenya—An application of classification and regression tree analysis
To guide soil fertility investment programmes in sub-Saharan Africa, better understanding is needed of the relative importance of soil and crop management factors in determining smallholder crop yields and yield variability. Spatial variability in crop yields within farms is strongly influenced by variation in both current crop management (e.g. planting dates, fertilizer rates) and soil fertility. Variability in soil fertility is in turn strongly influenced by farmers’ past soil and crop management. The aim of this study was to investigate the relative importance of soil fertility and crop management factors in determining yield variability and the gap between farmers’ maize yields and potential yields in western Kenya. Soil fertility status was assessed on 522 farmers’ fields on 60 farms and paired with data on maize-yield and agronomic management for a sub-sample 159 fields. Soil samples were analysed by wet chemistry methods (1/3 of the samples) and also by near infrared diffuse reflectance spectroscopy (all samples). Spectral prediction models for different soil indicators were developed to estimate soil properties for the 2/3 of the samples not analysed by wet chemistry. Because of the complexity of the data set, classification and regression trees (CART) were used to relate crop yields to soil and management factors. Maize grain yields for fields of different soil fertility status as classified by farmers were: poor, 0.5-1.1; medium, 1.0-1.8; high, 1.4-2.5 t ha-1. The CART analysis showed resource use intensity, planting date, and time of planting were the principal variables determining yield, but at low resource intensity, total soil N and soil Olsen P became important yield-determining factors. Only a small group of plots with high average grain yields (2.5 t ha-1; n = 8) was associated with use of nutrient inputs and good plant stands, whereas the largest group with low average yields (1.2 t ha-1; n = 90) was associated with soil Olsen P values of less than 4 mg kg-1. This classification could be useful as a basis for targeting agronomic advice and inputs to farmers. The results suggest that soil fertility variability patterns on smallholder farms are reinforced by farmers investing more resources on already fertile fields than on infertile fields. CART proved a useful tool for simplifying analysis and providing robust models linking yield to heterogeneous crop management and soil variables.
Impact of Gliricidia sepium intercropping on soil organic matter fractions in a maize-based cropping system
The gliricidia (Gliricidia sepium)/maize intercropping system holds promise for increasing productivity in maize-based cropping systems on depleted soils in Southern Africa. The effect of the intercrop on soil properties was investigated to better understand soil processes underlying maize yield response, soil nutrient recapitalization and soil carbon sequestration. Soil organic matter (SOM) fractions, particulate organic matter (POM), POM-carbon, POM-nitrogen, soil nutrient status and underlying soil characteristics were quantified on the 14th year of a gliricidia/maize intercrop establish in 1991 on a Ferric Lixisol in southern Malawi. A factorial design compared the intercrop and a sole maize crop at three rates of added inorganic nitrogen (N) and phosphorus (P). Gliricidia leaf biomass was incorporated into the maize three times per year. Soil was sampled to a 20 cm depth, post-harvest to analyze biophysical and chemical characteristics of soil organic matter, POM, POM-C and POM-N, as well as inorganic N, available P, exchangeable K+ and particle size distribution. The gliricidia/maize intercrop had a significant and positive effect on SOM, POM, and SOM fractions: SOM was 12% higher, POM 40%, POM-C 62%, and POM-N 86% higher in the gliricidia intercrop compared to sole maize, indicating nitrogen enrichment of POM. Nitrogen fertilizer was associated with modest increases in POM, 15% in gliricidia and 27% in sole maize. The impacts of these changes were directed mostly at increasing maize yields and increasing storage of soil nutrients over the short term, while decreasing the proportion of organic matter stored over the long term. Both the gliricidia/maize intercrop and increasing soil clay content were associated with significantly increased soil CEC. The gliricidia intercrop maintained CEC in coarse-textured soils over a 14-year time span, indicating a role for legume trees in intensified cropping of coarse-textured soils.
Understorey microclimate and crop performance in a Grevillea robusta-based agroforestry system in semi-arid Kenya
The influence of dispersed trees on microclimatic conditions, gas exchange and productivity of maize (Zea mays L.) in a Grevillea robusta-based agroforestry system in semi-arid Kenya was examined to test the hypothesis that the benefits of shade seen in savannah ecosystems may be outweighed by competition for below-ground resources. Meristem temperature, cumulative thermal time, intercepted radiation, spatial distribution of shade and gas exchange were determined for maize grown as sole crops, in an agroforestry system, or under shade nets providing 25 or 50% reductions in incident radiation to discriminate between effects of shade and below-ground competition. The major benefit of shade was to reduce exposure to the supra-optimal temperatures experienced in many tropical regions, and which are predicted to become increasingly common by climate change models. However, although trees decreased photosynthetic photon flux density (PPFD) incident on understorey maize by ca. 30%, the yield reduction was much greater than in the 25% shade net treatment in four seasons providing contrasting rainfall. Maize yield was unaffected by 50% artificial shade in the driest season (168 mm) but decreased with increasing shade when rainfall was high (628 mm). Shade reduced meristem temperature and delayed flowering by 5-24 days depending on treatment and seasonal rainfall. Thermal time to flowering in the agroforestry system doubled from 600 to 1200 C day as rainfall decreased. Photosynthetic and transpiration rates for understorey maize were similar to the 25 and 50% shade treatments when rainfall was high, but were ca. 10% of those for unshaded sole maize in dry seasons. PPFD-saturated photosynthetic rate was initially similar in all treatments but fell sharply in the agroforestry system as the season progressed. Radiation conversion coefficients did not differ between unshaded sole and understorey maize. The results suggest that the ameliorative influence of tree shade was greater in low rainfall seasons, as in savannah systems, but that potential benefits were outweighed by below-ground competition. This may be managed by root-pruning trees.
On-farm assessment of legume fallows and other soil fertility management options used by smallholder farmers in southern Malawi
This study evaluated the performance of tree legumes and other soil fertility management innovations used by farmers. The objectives of the study were to: examine the extent that farm attributes, typology of farmers and field management practices have affected the adaptation and use of agroforestry technologies for soil fertility management and compare the agronomic performance and farmer assessment of agroforestry and other soil fertility management options, across a wide range of farmer types and field conditions, with a view to establishing the contribution of management variables to variations in yield estimation. Maize yield and farmer rating were assessed in Type II (researcher-designed, farmer-managed), Type III (farmer-designed and managed) trials and extension farmers. Results from 152 farmers show that agroforestry increased the yield of maize by 54-76% compared to unfertilized sole maize used as the control. When amended with fertilizer, the yield increase over the control was 73-76% across tree species. This indicates that farmers who had combined agroforestry with inorganic fertilizer experienced increase in maize yield attributable to the synergy between organic and inorganic fertilizer. In gliricidia-maize intercropping, higher maize yield was obtained by farmers who pruned twice. Combination of two prunings and fertilizer use gave the highest yield increase (148%) over the control and the third pruning was superfluous when fertilizer was applied. Without fertilizer, maize yield in agroforestry plots intercropped with pigeon pea was higher than those plots without pigeon pea. Planting date, fertilizer application, use of agroforestry and maize variety explained about 44% of the variation in maize yield on farmers’ fields.