Soil Nitrate Test To Assess The Nitrogen Fertilizer Need For Tropical Soils: A Case Of Morogoro District

ABSTRACT

Soil nitrate test of Soil Doc protocol has potential to identify optimum N fertilizer requirements for optimizing economic return, while reducing environmental impact. The purpose of this study was to develop N fertilizer requirements for maize production based on the soil nitrate test for the tropical soils in Morogoro District, Tanzania using soil Doc Protocol. Composite soil samples were collected pre-planting (PPNT) and pre-topdressing (PTNT) of N fertilizers to determine soil NO3-N. The PPNT soils samples were also used for determining soil physical and chemical properties. The experiment was conducted in the two villages, the treatments consisted of two soil NO3- level (medium and high) , three nitrogen fertilizer rate: 80 kg N ha-1, 40 kg N ha-1, and control (0 kg N ha-1 arranged in a randomized complete block design (RCBD) with factorial treatment structure. Initial soil properties were medium salinity pH and extremely low organic carbon and available P for all soils in both villages. The results revealed that maize growth parameters (fresh weight, dry weight, grain yield and total N) increased significantly (p