Synchrony Relationships of Nitrogen Release and Plant Uptake in a Zimbabwean Sandy Soil Amended with Manure and Fertiliser Nitrogen

A study was conducted to assess N mineralization and plant uptake patterns in a sandy soil amended with cattle manure and inorganic N applied at zero or six weeks after planting. Manure was applied at a rate equivalent to 10 t ha ^-1 and the N at 100 kg ha ^-1 . Nitrogen mineralization, uptake and leaching in the field were estimated by an in situ incubation technique. Estimated N uptake was compared with the actual N uptake measured from maize plants. All manure treatments showed an initial immobilization of N in the first 8 weeks. Early application of N resulted in significantly more N mineralization in the manure compared to application at 6 weeks after planting. Estimated values of N leaching ranged between 0.67 g m^-2 and 4.22 g m^-2 which is 3% to 42% of applied N. Greatest amounts were leached from the N treatments. Nitrogen recovery ranged from less than 0% to 69% of applied N.