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Scientists discuss cropping systems for maintaining soil quality and available soil moisture at Tropentag 2012!

Fri, 09/21/2012 - 08:57 — De-Registered User
The session was moderated by Ronald F. Kuhne from the Georg-August-Universität Göttingen, Germany who introduced the speakers and welcomed all participants. The lead speaker was Birthe Paul from the International Centre for Tropical Agriculture (CIAT), who presented on the topic, “Impact of tillage and residue management on soil quality and crop productivity”. Birthe mentioned that 80% of soils in Sub-Saharan Africa are inherently low in soil fertility and that 65% of the soils are degraded by human activity. She further added that there is stagnating crop yields pegged at 1 tha-1 while 30 % of the population is affected by food shortage. According to her, Conservation Agriculture has the advantages of continuous minimum mechanical soil disturbance, permanent organic soil cover and diversification of crops grown in sequence or association and this potentially improves soil aggregate ability, soil aggregate organic carbon and crop yields. The study objectives were outlined as; 1. To bridge knowledge gaps by providing rigorous empirical evidence 2. To capture medium term effects of tillage and residue management on – soil aggregate stability, soil organic carbon and crop yields. The study was conducted in sub-humid western Kenya starting in 2003. In this experiment, maize and soybeans were used in rotation. Two factors were chosen namely, tillage (comprising of conventional and reduced) and residue (comprising of retained and removed). According to the speaker, the results showed that tillage has a significant influence on soils while the influence of residue was weak. It was also revealed that soil carbon had no significant influence at 0-15 cm soil depth. Maize yields did not differ much among different treatments of tillage and residue while for soybeans, the differences were quite significant. In conclusion she mentioned that; • Reduced tillage improved aggregate stability • Potential of Conservation Agriculture for climate change mitigation is overestimated • Weak residue effect might be due to low retention rate and termite removal • Soybean yields tended to be suppressed, especially in wet seasons • Future research should investigate minimum residue retention level

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