Effect of type and level of roughage offered to sheep and urine addition on compost quality and millet growth and production in the Sahel

A greenhouse trial was carried out at the International Crop Research Institute for the Semi-Arid Tropics (ICRISAT), at Sadore (13°15′ N, 2°18′ E), Niger. Experiments were conducted in conjunction with a feeding trial. The feeding trial yielded eight types of compost made from faeces and leftovers with or without urine addition from sheep fed either bush straw or millet stover offered at 60 or 80 g dry matter (DM) kg−1 live weight (LW). In the second trial the agronomic value of composts to a millet crop was evaluated. The level of roughage on offer did not affect compost quality. Urine addition increased N content in composts (P<0.05), but had no effect on P. Millet stover based composts contained 24% more N and 42.5% more P than composts made with bush straw (P<0.05). Urine addition enhanced millet growth between 15 and 60 days after planting (DAP), increased millet aboveground mass by a factor 2.8, and increased the efficiency of N and P use by 100% and 50%, respectively. Millet response (growth, phytomass, N and P uptake, apparent efficiency of N and P use) to urine addition was higher with millet stover based composts than with bush straw based composts (P<0.05). It was concluded that addition of urine during composting of roughage leftovers and faeces from stall-fed animals could significantly improve nutrient recycling and consequently the productivity of mixed farming systems of semi-arid West Africa.