Short‐Term Impacts of Conservation Agriculture on Soil Physical Properties and Productivity in the Midhills of Nepal

Abstract

Core Ideas Aggregation and time‐to‐pond were improved under conservation agriculture.Conventional practice had a higher sorptivity rate than conservation agriculture.Maize yields were similar for conservation agriculture and conventional practice in the first year of production.Maize yields were less in conservation agriculture than in conventional practice in the second year due to patchy plant stands in conservation agriculture.There were no differences in yield between conservation agriculture and conventional practice for rapeseed or wheat. Conservation agriculture (CA) is a management system characterized by zero or minimum tillage, permanent soil cover with crop residue or plant growth, and crop rotation. This study investigated the impact of conservation tillage, crop type, and planting date on crop productivity and the soil physical properties for 2 yr following conversion to CA. After 2 yr, average mean weight diameter of dry aggregates for the 0‐ to 5‐cm and 5‐ to 10‐cm soil depths were 45 and 24% greater in the CA treatment than the conventional practice (CP) treatment, respectively. However, soil sorptivity was about three times slower in CA than in CP for rapeseed (Brassica napus L. toria) rotation treatments, but only 62% slower in CA than CP for wheat (Triticum aestivum L.) rotation treatments. Soil bulk density to a depth of 15 cm was greater in CA (1.30 g cm−3) than CP (1.24 g cm−3), but only for late‐planted treatments. Maize (Zea mays L.) yields for CA were not different from CP in the first year, but were 1.4 Mg ha−1 for CA and 5.0 Mg ha−1 for CP in the second year due to poor stand establishment under CA. There were no effects of CA on dry‐season rapeseed and wheat. Results suggest that during the transition of CP to CA, soil physical properties can be improved but yields may remain constant or decline. Achieving equivalent yield outcomes between CA and CP will largely depend on equivalent stand establishment.