Effect of organic and intensive farming on NPK balance in soil

Effect of organic farming on balance of NPK was researched on the farm of organic production of the Agroecological Center at Lithuanian University of Agriculture. Having calculated NPK balances of field crop rotations I and II on the farm in the period of 1997–2004, NPK balance was found negative. With organic production more nitrogen has been imported in the field of rotation I, which had been fertilized with manure, while amounts of imported phosphorus and potassium were greater in field rotation II, where legumes were grown and no manure applied. In cases where certified potassium and phosphorus fertilizers had been applied, a positive balance of phosphorus and potassium was obtained. Application of a 40 t ha-1 of litter manure once every four years does not ensure a positive nitrogen balance. Effect of intensive farming when plants are fertilized with different rates of NPK fertilizers on balance of nutritional materials in plants was researched in the period of 2001–2005 in Elmininkai (region of Anyksciai) in phosphorus and potassium rich soils. Having calculated fertilizer rates in crop rotations (wheat, potatoes, barley, perennial grasses) and with the account to amounts of nutritional materials found in soil (N50P23K51 + 60 t ha-1 of manure once every crop rotation) their balance was close to zero. Application of average rates of this fertilizer (N51P60K78 + manure) with no account to agrochemical indexes, a positive NPK balance was obtained. As the result of this, nutritional materials unused by plans can be washed out and pollute the environmentLietuvos žemdirbystės instituto Agrocheminių tyrimų centras, lzi_atc@euteka.ltVytauto Didžiojo universitetasŽemės ūkio akademij