Crop Yields Response To Conservation Farming And Spatial-Temporal Effects In Zambia

We examined crop yields along a wide environmental gradient and spatial dynamics in soil organic matter in response to conservation farming (CF) in Zambia. Maize yields from farmer managed CF and traditional farming (TF) were not significantly different with over 280 on-farm trials with varying soil properties, management practices and environmental covariates. Principle component analysis (PCA) identified inappropriate management practices (planting and insufficient weeding), of which 25% of total variability were major factors restricting CF yields. TF yields were limited by both amount and types of inputs that explained 26 % of total variability. With addition of different organic and inorganic amendments, average CF yield ranged from 1 to 4 t ha-1, with highest in wetter region (3.4±7.9 t ha-1) and lowest (2.1±6.8 t ha-1) in degraded plateaus. Combined additions of inorganic fertilizer (NP-K at 200-100-100 kg ha-1) with biochar and manure achieved the highest effect in degraded plateau with yield increase of 320% and 300% respectively as compared to organic matter additions of manure (46%) and gliricidia (24%) in the same region. PCA established pre-existing soil fertility is the major factor in all sites for improved yields and nutrient uptake with organic additions (P