Tag: crop systems
Effects of soil management on aggregation and organic matter dynamics in sub-Saharan Africa
Maintenance of soil organic matter (SOM) is important for soil quality and agricultural productivity. However, little is known about the effects of management practices of different intensities on soil aggregation and SOM dynamics in tropical arable cropping systems of sub-Saharan Africa. We investigated the influence of land use practices and management intensity on soil aggregation and SOM dynamics across 12 long-term field experiments in eastern and western Africa. Aggregate size distribution and SOM were measured in arable systems under contrasting management intensities of high carbon, low carbon and a fallow. Aggregate stability indices and SOM were generally higher in the fallow compared to the arable systems. Fallowing and high carbon inputs in arable soils, significantly improved aggregate stability and carbon (C) and nitrogen (N) stabilization in whole soil, and in aggregate fractions. In contrast, no significant improvements in soil aggregation and C and N stabilization were found when organic inputs were either applied in low quantities or not applied at all, thus resulting in low carbon in soils. Our study showed that fallowing and long-term application of organic amendments alone or in combination with mineral fertilizers were the best among the practices tested in this study, for enhanced C and N stabilization in soils with the subsequent benefits of improving soil physical and chemical properties. These results emphasize the importance of management for sustaining soil quality. It is recommended that fallowing be an integral part of sustainable soil management strategies in these regions.
Data in brief on inter-row rainwater harvest and fertilizer application on yield of maize and pigeon-pea cropping systems in sub humid tropics
Data in this article presents rainfall variability in the season and between seasons, yield of maize (Zea mays cv. TMV1) and pigeon-pea (Cajanus cajan cv. Babati White) under sole crop and intercropping. Yield of maize and pigeon-pea is analyzed under inter-row rainwater harvesting practices and fertilizer application in the field. Sole cropping and intercropping biological and/or economic yield are used to determine land use efficiency through land equivalent ratio. Comparisons between sites and seasons are done using a T-test.
Local knowledge on the role of trees to enhance livelihoods and ecosystem services in Ho Ho Sub-watershed, north-central Viet Nam
Understanding how local people view and value the role of trees in enhancing livelihoods and environmental quality is the key to increasing resilience in agricultural landscapes through tree planting. In the Ho Ho sub-watershed, north-central Viet Nam, which is highly exposed to climate change and variability, we investigated local knowledge on the role of trees that involved people upstream and downstream in the sub-watershed. The respondents were requested to identify the different roles of tree-based and annual crop systems in their landscape to livelihood and the environment, and then to rank these roles to reveal the primary function of each landuse system. We found that local knowledge on the roles of each landuse type, both in upstream and downstream communes, was influenced by the household land holding size and the actual contribution to household income as well. This, for example, explains the higher appreciation of acacia than agarwood in terms of livelihood and environmental functions. In the sub-watershed, the average land holding size per household for acacia plantation was 1.3 ha, while agarwood trees were planted in homegardens with a delayed harvesting time (15 years after planting compared to 7 years for acacia). Different responsibilities in agricultural activities between males and females in the family, contributed to contrasting responses between the male and female groups on the role of tree-based and annual crop systems in household income. Men regarded annual crops as a more important source of income than trees, whereas women asserted the opposite. In the sampled households, financial management and private consumption provision were two tasks mostly handled by women, and this likely explains the gender sensitivity. We conclude that local people in the upstream and downstream communes of the sub-watershed recognised well the important roles of trees to livelihood and environmental quality, but in actual implementation, they always prioritised livelihood over environmental issues, especially in relation to tree planting on their own land. Environmental issues were only an option considered for unallocated areas such as protection forest, or for allocated lands not suitable for planting due to physical barriers such as high elevation or steep slopes.
Critical slope length for soil loss mitigation in maize-bean cropping systems in SW Kenya
Soil 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.