Run-off, Soil Moisture, and Weed Management Strategies to Increase Water Productivity in Rain-fed Crops in Tanzania

Publication Type

Contribution to conference

Authors

Schappert, A., Schaffert, A., Germer, J., Asch, F.

Year of publication

2017

Published in

Future Agriculture: Socio-ecological transitions and bio-cultural shifts

Conference name

Tropentag

Conference location

Bonn

Conference date

20-22 September 2017

Smallholder crop production systems in the semi-arid Dodoma region frequently sufferfrom drought-induced yield losses due to inadequate rainfall distribution and erratic rainfallevents. The 30 year average rainfall amount of 500 mm during the rainy-season indicatesthat in general precipitation is sufficient for the crops to mature. Run-off managementcould reduce the effects of intra-season variability in precipitation and in combination withimproved weed management is likely to improve overall soil moisture availability which inturn may result in more stable yields.The aim of this study was to analyse the potential of i) run-off management throughtied-ridges, ii) minimal irrigation to keep the soil moisture above the permanent wiltingpoint and iii) weed management to stabilise yields in pearl millet, sorghum, maize, andsunflower by improving water productivity.Due to soil surface modification, tied-ridges (i) collect water during rainfall events andthus increase the infiltration. Minimal irrigation requirements were set to 50 % of the cropwater requirements following the FAO-56 methodology and supplied via drip irrigation (ii).The weeding treatments (iii) comprised clean weeding (4–5 times weeding) and farmer’sweeding practice (once after emergence and once after canopy closure). The experiments were conducted at the Agricultural Research Institute Makutupora,Tanzania, during the wet season from January until May 2015 and 2016. Soil moisturewas measured frequently using a PR2Profile Probe. Leaf area, crop development stages,and biomass accumulation and partitioning were determined at regular intervals, and yieldcomponents were determined at harvest.The gained dataset helped to explore the influence of differing soil moisture levels onbiomass production and crop development stages. Furthermore, ANOVA with post hocTukey-Test (P≤0.05) was analysed to evaluate the impact of run-off, soil moisture ma-nagement and lower weeding frequencies on crop productivity. Tied-ridges and minimalirrigation generally increased grain yields by 80 — 99 % in 2015 and by 16 — 37 % in 2016.The yield-increasing effects were more pronounced in 2015 due to the very low yieldin