Kebutuhan Nitrogen Tanaman Kedelai Pada Tanah Mineral Dan Mineral Bergambut Dengan Budi Daya Jenuh Air

The development of soybean in tidal land is faced with problems such as physical, chemical and biological soil properties, that includes high organic matter, high soil acidity, toxicity of Fe and Al, and deficiency of nutrients N, P , K, Ca and Mg. N content is high (> 0.51%) but with low availability. The research objective is to determine the dose and timing of N, P and K fertilizer application in accordance with the needs of soybean crops in order to have optimal growth and yield per unit of land in mineral and peaty mineral soil in tidal swamp land. The research was conducted in mineral and peaty mineral soil of tidal swamp land type C and B, District of Tanjung Lago, Banyuasin, South Sumatera from April to August 2014. The experiment was arranged following split plots design. Wilis and Tanggamus varieties as main plot, application time: 2, 3, 4 WAP, 2, 3, 4, 5 WAP, and 2, 3, 4, 5, 6 WAP as sub plots and fertilizer concentration: 7.5, 10, 12.5 dan 15.0 g/l water as subsub plots with spraying volume of 400 l/ha. Research results showed that mineral soil, dry weight of nodules and Wilis biomass increased with increasing frequency time of fertilizer application, while Tanggamus more fluctuated and declined at higher frequency of fertilizer application. Interaction of Wilis variety, time of fertilizer 2-6 WAP and concentration of 15 g N/I generated the highest yield of 3,5 ton/ha. In the peaty mineral soil, dry weight of nodules and biomass were not significantly different. Wilis productivity tends to decrease with increasing N fertilizer concentrations. Tanggamus productivity tends to increase with increasing N fertilizer concentration at all level of time of fertilizer application. Tanggamus tends to generate higher productivity of 3,2 ton/ha at a concentration of 15 g N/I with time of fertilizer application 2-4 MST. Application of low concentration N at higher frequency of fertilizer application or otherwise, was able to improve the productivity of soybeans in soil with high pyrite content