Medium-term impact of tillage and residue management on soil aggregate stability, soil carbon and crop productivity
Paul, B.K. ; Vanlauwe, B. ; Ayuke, F. ; Gassner, A. ; Hoogmoed, M. ; Hurisso, T.T. ; Koala, S. ; Lelei, D. ; Ndabamenye, T. ; Six, J. ; Pulleman, M.M. - \ 2013
Agriculture, Ecosystems and Environment 164 (2013)1. - ISSN 0167-8809 - p. 14 - 22.
organic-matter dynamics - conservation agriculture - no-till - africa - systems - nitrogen - kenya - stabilization - protection - yields
Conservation agriculture is widely promoted for soil conservation and crop productivity increase, although rigorous empirical evidence from sub-Saharan Africa is still limited. This study aimed to quantify the medium-term impact of tillage (conventional and reduced) and crop residue management (retention and removal) on soil and crop performance in a maize–soybean rotation. A replicated field trial was started in sub-humid Western Kenya in 2003, and measurements were taken from 2005 to 2008. Conventional tillage negatively affected soil aggregate stability when compared to reduced tillage, as indicated by lower mean weight diameter values upon wet sieving at 0–15 cm (PT <0.001). This suggests increased susceptibility to slaking and soil erosion. Tillage and residue management alone did not affect soil C contents after 11 cropping seasons, but when residue was incorporated by tillage, soil C was higher at 15–30 cm (PT*R = 0.037). Lack of treatment effects on the C content of different aggregate fractions indicated that reduced tillage and/or residue retention did not increase physical C protection. The weak residue effect on aggregate stability and soil C may be attributed to insufficient residue retention. Soybean grain yields tended to be suppressed under reduced tillage without residue retention, especially in wet seasons (PT*R = 0.070). Consequently, future research should establish, for different climatic zones and soil types, the critical minimum residue retention levels for soil conservation and crop productivity.
|Effects of conservation agriculture on crop yields, soil aggregation, and C & N dynamics in a soybean-maize rotation in western Kenya
Paul, B.K. ; Ayuke, F. ; Gassner, A. ; Hoogmoed, M. ; Hurisso, T.T. ; Lelei, D. ; Ndabamenye, T. ; Six, J. ; Vanlauwe, B. ; Pulleman, M.M. - \ 2011
In: Abstract Book of the Wageningen Conference on Applied Soil Science on Soil Science in a Changing World, Wageningen, The Netherlands, 18-22 September2011. - - p. 211 - 211.
Reduced tillage systems and controlled traffic farming (CTF) are being implemented in the Netherlands to lessen compaction and improve soil physical quality. Changes observed in soil physical quality after reducing tillage and starting controlled traffic are often attributed to ecosystem engineers such as earthworms. Through the burrowing and casting behaviours of diverse earthworm species these soil physical functions may be affected differentially between reduced tillage systems. It was hypothesized that reduced tillage systems, where soil is not inverted during tillage, and controlled traffic will promote earthworm density and diversity and therefore encourage an improvement in soil physical quality (soil water retention and infiltration). Two replicated field experiments in randomized complete block designs were performed on organic farms in Flevoland, the Netherlands. The soils are marine loams and climatic data was collected from nearby weather stations. Different tillage treatments with or without controlled traffic were compared. Earthworm abundance, biomass and species were assessed during biannual sampling in the spring and fall of 2009, 2010 and 2011. Soil water retention, infiltration, penetration resistance, aggregate stability and saturated hydraulic conductivity were measured in the fall of 2010 and spring of 2011. Controlled traffic showed a significant positive effect on earthworm density, infiltration capacity and reduced penetration resistance. Data on the effect of tillage system is thus far not conclusive, possibly due to insufficient time for changes to occur, however data from an additional season will be added for this conference