Biophysical interactions in tropical agroforestry systems

sequential systems, simultaneous systems Abstract. The rate and extent to which biophysical resources are captured and utilized by the components of an agroforestry system are determined by the nature and intensity of interac-tions between the components. The net effect of these interactions is often determined by the influence of the tree component on the other component(s) and/or on the overall system, and is expressed in terms of such quantifiable responses as soil fertility changes, microclimate modification, resource (water, nutrients, and light) availability and utilization, pest and disease incidence, and allelopathy. The paper reviews such manifestations of biophysical interactions in major simultaneous (e.g., hedgerow intercropping and trees on croplands) and sequential (e.g., planted tree fallows) agroforestry systems. In hedgerow intercropping (HI), the hedge/crop interactions are dominated by soil fertility improvement and competition for growth resources. Higher crop yields in HI than in sole cropping are noted mostly in inherently fertile soils in humid and subhumid tropics, and are caused by large fertility improvement relative to the effects of competition. But, yield increases are rare in semiarid tropics and infertile acid soils because fertility improvement does not offse

Pigeonpea (Cajanus cajan L. Millsp.): An Ideal Crop for Sustainable Agriculture

Pigeonpea [Cajanus cajan (L.) Millsp.] is traditionally cultivated as an annual crop in semi-arid regions of the world. It has a number of characteristics such as diverse maturity time, drought tolerance and natural out-crossing which makes it unique among legumes. These traits not only allow its cultivation in diverse environments and cropping systems, but also permit implementation of different breeding methods. Pigeonpea is a crop of sustainable agriculture and poor crop management, exposure to diseases and pests coupled with unpredictable rains hinder crop improvement activities. However, recently partial out-crossing has been exploited to develop cytoplasmic male-sterility (CMS) based hybrid breeding technology. Thus far, three hybrids have been released for cultivation with yield advantages of 30–50% over standard varieties. Pigeonpea R&D now also enjoys a wealth of genomics resources such as a draft genome sequence, resequencing data, candidate genes and markers associated with key traits. Genomics and breeding efforts are underway to make pigeonpea a more sustainable crop and to unlock the genetic diversity present in germplasm to develop new cultivars rapidly

Potential use of forage-legume intercropping technologies to adapt to climate-change impacts on mixed crop-livestock systems in Africa: a review

This paper summarizes effects of forage-legume intercropping on grain and fodder yield, land equivalent ratio, residual soil fertility, disease and insect pest reduction in mixed crop-livestock systems in Africa. In particular, it discusses the potential benefit of forage-legume intercropping in improving productivity, resource use efficiency and resilience of the system under climate change, which enhances adaptation to climate change and possibly provides the co-benefit of reducing greenhouse gases in sub-Saharan Africa. Research undertaken in Africa demonstrates that intercropping forage legumes with cereals improves overall yield and soil fertility, and reduces the risk of crop failure owing to rainfall variability, diseases, weeds and pests. When the forage from intercropped legumes is provided to animals it improves the digestibility of poor-quality feed, animal performance and efficiency of roughage feed utilization by ruminants. Additional role that legumes may play include lowering erosion and the loss of organic matter, reducing nitrogen leaching and carbon losses, and promoting carbon sequestration. Nitrogen fixed by legumes is safer than nitrogen from inorganic fertilizers. Despite the many benefits of forage legume intercropping the current adoption rate in sub-Saharan Africa is very low. Future research aimed at selection of compatible varieties, appropriate plant geometry and temporal arrangement of the various intercrops under different locations and management scenarios, as well as minimizing the confounding effects of water, soil, light, microclimate, and seeds could enhance adoption of the technology in Africa.http://link.springer.com/journal/101132018-08-30hb2017Animal and Wildlife SciencesPlant Production and Soil Scienc