1,720,982 research outputs found
Integrating legumes in mixed crop-livestock systems in east Africa: Farmers' perceptions, ecosystem services and support for decision making
Full text linkChallenges faced by smallholder farmers in east Africa include limited access to inputs, small farm sizes, and erratic rainfall patterns. Legume intensification and species diversification have been recommended for improving food and nutritional security, controlling soil erosion, improving soil fertility, supplying income and providing fuel. The aim of the thesis was to assess the various contributions legumes make in integrated crop-livestock systems and to facilitate their efficient use. The approaches used included: 1) an on-farm survey of 268 farmers in Kenya and Democratic Republic of the Congo to assess farmers’ perceptions of legumes and their functions; 2) a metaanalysis on the effects of crop management practices on legume productivity and biological nitrogen fixation (BNF) in sub-Saharan Africa; 3) an on-farm experiment in Kenya investigating the effects of crops and crop mixtures including legumes on soil erosion control; and 4) providing inputs from literature review and experimental results to further develop the LegumeCHOICE decision support tool. Results showed that farmers appreciated legumes more for their food and income functions than for provision of fodder, fuel, soil fertility or erosion control. Furthermore, according to survey work, the concept of “legumes” had little meaning for farmers. The metaanalysis showed that crop management practices directly influenced legume productivity. Intercropping increased the total land equivalent ratio (LER). Focusing on the legume component, pigeon pea (Cajanus cajan) had a relative LER of 90%, while for species such as groundnut (Arachis hypogea) and common bean (Phaseolus vulgaris) the figure was around 60%. Inoculation and phosphorus (P) application increased legume grain and biomass yield, and species and soil type helped explain the variation of legume productivity in response to those management practices. Inoculation also increased the amount of nitrogen (N) fixed by legumes. Experimental work showed that incorporating different crop types and crop mixtures with legumes increased rainfall infiltration and earthworm population, and reduced runoff and soil erosion. Calliandra hedgerows, mulching and sole Mucuna reduced soil erosion and runoff more than maize/common bean intercropping. Developing literature-derived values as a complement to the expert scores, which presently underlie the LegumeCHOICE tool improved the relationships between the scoring and actual provision of food, livestock feed and soil fertility improvement using grain and biomass yield and BNF as proxies. This thesis shows that farmers in east Africa have some knowledge about legumes although their perception of the various functions legumes provide is limited. Despite heterogeneity of smallholder farming systems, legumes respond consistently to intercropping, inoculation and P-application. Combining literature values with expert scores enhanced the validity of the LegumeCHOICE tool for supporting farmer decision making
Crop Residue Management in Conservation Agriculture Systems in Zimbabwe Smallholder Farming Sector: Importance, Management Challenges and Possible Solutions
Full text linkConservation agriculture (CA) is promoted as a cropping system that has potential to alleviate poor crop yields in smallholder farming while protecting the environment. It involves maintenance of permanent soil cover, diverse crop rotations and/or interactions; and minimum soil disturbance. CA is associated with crop residue management challenges due to low crop biomass yields and crop-livestock interactions in Zimbabwean smallholder farming sector. There is competition on crop residue uses causing challenges in retaining adequate crop residues for full benefits of using residues to be realised. Among the crop residues management options fencing fields reduces the chances of crop residues grazing by free roaming cattle during the dry season. Construction of rakes to pile up crop residues where cattle cannot access has been practiced in some communal areas. Farmers have practised the system of taking the crop residue harvest to homesteads into protected areas to reduce risk of grazing. Farmers may use fences around fields to reduce access into fields. However, all these management options require an investment from the farmers who are resource constrained. Farmers may use non-crop residues such as thatch grass and reduce competition for crop residue use where farmers feed them to livestock during the dry season
Weed Management in Zimbabwean Smallholder Conservation Agriculture Farming Sector
Full text linkWeed management is one of the major constraints in the Zimbabwe smallholder farming sector contributing to smallholder poor yields, hence there is need to identify cropping systems that have potential to reduce weed pressure while improving crop yields. Conservation agriculture has been suggested as one of these farming systems. The implementation of CA three key principles reduces weed pressure even when the use of herbicides is minimised. Crops included in crop rotations, intercropping or relay cropping may have faster growth rate than weeds hence, have a comparative advantage over weeds. Maintenance of permanent soil cover through crop residues impedes weed germination thereby reducing weed population. Elimination of ploughing also reduces the chances of bringing buried weed seeds to the surface where their chances for germination are high. Hence, some seeds lose viability thus reducing weed density. Weed seeds accumulate at the surface, when allowed to set seed, increasing their exposure to predation resulting in reduction of weed density over time. The use of herbicides ensures that the fields are weed free as the season’s progress thus ensuring better yields at the end of each growing season. Hence, weeds are reduced in CA systems over time despite the weeding option used
Management of maize-legume conservation agriculture systems rather than varietal choice fosters human nutrition in Malawi
Full text linkMalawi smallholder farmers are facing climate-induced challenges that have increased food and nutrition insecurity in the country, thus sustainable intensification practices has been widely recommended. The objective of this study was to assess the effects of cropping systems with improved varieties on total system productivity and nutrition under different environments. The study involved on-farm experiments in ten communities in Central and Southern Malawi, incrementally established from 2005/2006 to 2018/2019 cropping seasons. Each community had six demonstration plots with three main treatments: conventional ploughing (CP): sole maize grown on seasonally constructed ridges and furrows; no-tillage (NT): sole maize grown on retained ridges with minimum soil disturbance and residue retained; and Conservation agriculture (CA): maize intercropped either cowpea, pigeon pea or groundnut on retained ridges as in NT. Our results show that total system nutrition was higher in CA treatments than NT and CP. The yields of maize were at least 800 kg ha-1 higher in CA and NT than CP despite the variety that was grown. Legume yields were also higher under CA and NT than CP. High protein yield was observed in CA systems (at least 100 kg ha-1 higher than CP) where maize and legume intercrops were rotated with grain legumes. Our results show nutrients and energy gains in CA and NT systems that can be invested in practices that increases the resilience of smallholder farmers to climate change. Conservation agriculture and NT systems have more influence on productivity of smallholder farms, despite the genotypes used (hybrids or OPVs)
Integrating legumes in mixed crop-livestock systems in east Africa: Farmers' perceptions, ecosystem services and support for decision making [Elektronisk resurs]
No full textChallenges faced by smallholder farmers in east Africa include limited access to inputs, small farm sizes, and erratic rainfall patterns. Legume intensification and species diversification have been recommended for improving food and nutritional security, controlling soil erosion, improving soil fertility, supplying income and providing fuel. The aim of the thesis was to assess the various contributions legumes make in integrated crop-livestock systems and to facilitate their efficient use. The approaches used included: 1) an on-farm survey of 268 farmers in Kenya and Democratic Republic of the Congo to assess farmers’ perceptions of legumes and their functions; 2) a metaanalysis on the effects of crop management practices on legume productivity and biological nitrogen fixation (BNF) in sub-Saharan Africa; 3) an on-farm experiment in Kenya investigating the effects of crops and crop mixtures including legumes on soil erosion control; and 4) providing inputs from literature review and experimental results to further develop the LegumeCHOICE decision support tool. Results showed that farmers appreciated legumes more for their food and income functions than for provision of fodder, fuel, soil fertility or erosion control. Furthermore, according to survey work, the concept of “legumes” had little meaning for farmers. The metaanalysis showed that crop management practices directly influenced legume productivity. Intercropping increased the total land equivalent ratio (LER). Focusing on the legume component, pigeon pea (Cajanus cajan) had a relative LER of 90%, while for species such as groundnut (Arachis hypogea) and common bean (Phaseolus vulgaris) the figure was around 60%. Inoculation and phosphorus (P) application increased legume grain and biomass yield, and species and soil type helped explain the variation of legume productivity in response to those management practices. Inoculation also increased the amount of nitrogen (N) fixed by legumes. Experimental work showed that incorporating different crop types and crop mixtures with legumes increased rainfall infiltration and earthworm population, and reduced runoff and soil erosion. Calliandra hedgerows, mulching and sole Mucuna reduced soil erosion and runoff more than maize/common bean intercropping. Developing literature-derived values as a complement to the expert scores, which presently underlie the LegumeCHOICE tool improved the relationships between the scoring and actual provision of food, livestock feed and soil fertility improvement using grain and biomass yield and BNF as proxies. This thesis shows that farmers in east Africa have some knowledge about legumes although their perception of the various functions legumes provide is limited. Despite heterogeneity of smallholder farming systems, legumes respond consistently to intercropping, inoculation and P-application. Combining literature values with expert scores enhanced the validity of the LegumeCHOICE tool for supporting farmer decision making.</p
Friends or foes? Population dynamics of beneficial and detrimental aerial arthropods under Conservation Agriculture
No full textArthropod pest control is one of the most critical agronomic practices in cereal-based cropping systems. Cropping systems that preserve or promote biological pest control agents are more desirable. Data collected from a long-term trial at the Monze Farmer Training Centre (MFTC) from 2009 to 2012 was used to compare effects of different Conservation Agriculture (CA) systems with conventional practices (CP) on arthropod species diversity and populations with specific emphasis on beneficial and detrimental aerial arthropods. Up to 13 arthropod orders comprising of 40 species were identified in the cropping systems and their population density differed in years and cropping systems. Higher diversity was observed in CA systems in all years based on the Shannon-Weiner indices ranging from 0.4 to 2. However, a CP system with no rotations (CP-M) showed comparable results in the year with low rainfall. Community evenness increased in the same year with a value of 0.46. More beneficial and detrimental arthropods were recorded in a CA system with a three-year rotation of maize, cotton and sunnhemp reaching up to 9533 individuals ha(-1). The CP-M recorded the highest increase in detrimental arthropods from 2009 to 2012. A canonical correspondence analysis did not show a clear-cut association of both CA and CP systems with either beneficial or detrimental arthropods. However, associations were more driven by seasonal effects. Reduced soil disturbance, crop residue retention and crop diversity in CA systems preferentially attracted beneficial arthropods while preserving existing favourable arthropods. Conventional tillage systems often disturbed arthropod habitats, disrupted their life cycles leading to lower biological activity. Increased biodiversSity from CA systems may therefore support biological control
Critical slope length for soil loss mitigation in maize-bean cropping systems in SW Kenya
No full textSoil erosion and land fragmentation threaten agricultural production of sub-Saharan African highlands. At our study site in Western Kenya, farm size is mostly < 2 ha, laid out in narrow strips in slope direction and ploughed downhill. Soil conservation measures like hedgerows and green manures can reduce effective slope length for erosion, but compete with crops for space and labour. Knowledge of critical slope length can minimise interventions and trade-offs. Hence, a maize-bean intercrop (MzBn) slope length trial on 20, 60 and 84 m long plots, replicated twice on three farms was carried out in Rongo, Migori County, during one rainy season. Soil loss from 84 m slope length (SL) plots was 250 % higher than from 60 m and 710% higher than from 20 m plots, while soil loss from 20 and 60 m plots did not differ (p < 0.05). Conversely, runoff was lower on the 84 m than on the 60 m (p < 0.05) or the 20 m SL (p < 0.05). Across all three farms slope gradient and length had highest explanatory power to predict soil loss. At individual farm level, under similar slope and soil texture, slope length and profile curvature were most influential. Regarding results of the slope length experiments, food crop plot lengths < 50 m appear essential considering soil loss, sediment load, and soil loss to yield ratio under the given rainfall, soil and slope (10-14%) conditions. Our results call for designing integrating slope length options and cropping systems for effective soil conservation. We recommend planting Mucuna and Calliandra-hedgerows as buffer strips below the critical slope length, and legume cash crops and maize uphill. Such approaches are critical against the backdrop of land fragmentation and labour limitation to sustainably maximise food production from the available land area in the region. (c) 2020 Elsevier B.V. All rights reserved
Management of maize-legume conservation agriculture systems rather than varietal choice fosters human nutrition in Malawi [Elektronisk resurs]
No full textMalawi smallholder farmers are facing climate-induced challenges that have increased food and nutrition insecurity in the country, thus sustainable intensification practices has been widely recommended. The objective of this study was to assess the effects of cropping systems with improved varieties on total system productivity and nutrition under different environments. The study involved on-farm experiments in ten communities in Central and Southern Malawi, incrementally established from 2005/2006 to 2018/2019 cropping seasons. Each community had six demonstration plots with three main treatments: conventional ploughing (CP): sole maize grown on seasonally constructed ridges and furrows; no-tillage (NT): sole maize grown on retained ridges with minimum soil disturbance and residue retained; and Conservation agriculture (CA): maize intercropped either cowpea, pigeon pea or groundnut on retained ridges as in NT. Our results show that total system nutrition was higher in CA treatments than NT and CP. The yields of maize were at least 800 kg ha-1 higher in CA and NT than CP despite the variety that was grown. Legume yields were also higher under CA and NT than CP. High protein yield was observed in CA systems (at least 100 kg ha-1 higher than CP) where maize and legume intercrops were rotated with grain legumes. Our results show nutrients and energy gains in CA and NT systems that can be invested in practices that increases the resilience of smallholder farmers to climate change. Conservation agriculture and NT systems have more influence on productivity of smallholder farms, despite the genotypes used (hybrids or OPVs)
Tillage and crop rotations enhance populations of earthworms, termites, dung beetles and centipedes: evidence from a long-term trial in Zambia
No full textMacro-organisms contribute significantly to soil fertility improvement. The influence of conservation agriculture (CA) in southern Africa on their populations has not yet been fully understood. Thus, the objective of the current study was to evaluate the effects of CA and conventional tillage on below ground biological activity in a CA long-term trial in Monze, Zambia from 2011 to 2013. The study had ten treatments which differed by tillage systems (conventional ploughing, planting basins and direct seeding) and crop diversification intensity (sole cropping, 2- or 3-year crop rotations) involving maize, cotton and sunn hemp. These factors were combined to create rotation-tillage (RotTill) treatments. Sampling of macrofauna was done once per year using a metal frame measuring 0.25 m(2), hand-sorted to 30-cm depth. RotTill treatments had a significant effect on earthworms (Lumbricus terrestris), termites (Coptotermes formosanus), dung beetles (Scarabaeus viettei) and centipedes (Lithobius forficatus). Earthworms and termites were more abundant in CA treatments than in conventionally ploughed (CP) treatments. Biota diversity was generally higher in CA treatments than in CP controls. Conventional mouldboard ploughing generally reduced macrofauna, thus affecting biological soil fertility and the beneficial effect of the interactions of these organisms with the soil. CA treatments had the highest maize grain yields throughout the study period. Based on the results, reduced tillage systems and crop rotations increase biological activity shown by increased densities of termites and earthworms
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