INFLUENCE OF DIFFERENT FERTILIZERS ON NPK CONTENT IN SOIL, IN CONSERVATION AGRICULTURE SYSTEM
This paper presents the results obtained from an experiment carried out in conservation agriculture system. Six types of fertilizers, i.e. N, NP, NPK and potassium humate NPK that contain various forms of nitrogen were tested. The experiments placed on cambic phaeozem at SCDA Teleorman were conducted using soybeans as crops, and fertilizers dosages of 50, 100, 150 and 200 kg N/ha. The influence of fertilizers on the nitrogen, phosphorus, potassium, content in the soil after the harvest was investigated. Soil samples were collected at a depth of 0-20 cm. The laboratory tests were performed on conditioned soil samples. The experimental data was statistically processed using analysis of variance.
It was observed that the use of fertilizers increased of the nitrogen content from the soil from 0.157% for the unfertilized sample to 0.189% for the sample fertilized with NPK 15:15:15 at the application dosage of 100 kg N / ha (21.8%). The phosphorus content increased from 72 ppm P2O5 in the case of the unfertilized sample to 98 ppm P2O5 for the sample fertilized with NP 20: 20: 0 (200 kg / ha dosage).