BIOCHEMICAL METHOD OF FORECASTING NITROGENOUS FERTILIZER DOSES FOR PREDETERMINED CROP YIELD ON HUMIC PODZOL SOIL Russian patent published in 2005 - IPC

FIELD: agriculture, agronomic chemistry, agronomic ecology, soil biology, and chemical analysis of soil.

SUBSTANCE: method involves determining content of mineral nitrogen and potentially mineralizable nitrogen provided by soil incubation at temperature of 34-36°C for 7-8 days; converting mineral and potentially mineralizable soil nitrogen to solution by boiling incubated soil suspension in water in the ratio of 1:5 during 20 min for sandy, sandy loam and medium loamy soil and during 30 min for heavily loamy soil; subjecting aqueous extraction of soil sample to analysis by means of Kieldal apparatus for determining nitrogen content actually available to plants under light alkaline hydrolysis conditions; determining nitrogen content potentially available to plants under drastic alkaline hydrolysis conditions; forecasting fertilizer nitrogen dose on the basis of nitrogen content actually available to plants for predetermined yield of specific crop with the use of coefficient of assimilation by plants of soil nitrogen and fertilizers, and amount of nitrogen needed for production of 1 centner/hectare of product from formula: ,

where D is forecast fertilizer nitrogen dose; N is kg/hectare; Y_c is crop yield for which fertilizer nitrogen dose is calculated, centner/hectare; C is amount of nitrogen needed for production of 1 centner/hectare of product of designed crop, kg/hectare; N_aa is amount of nitrogen in soil actually available to plants, kg/hectare; 0.4 is coefficient of usage by plants of available nitrogen from fertilizer, %. Method may be used for evaluation of humic podzol soil with regard to its nitrogenous state, forecasting of need for nitrogenous fertilizer by plants, determining stock of nitrogen available to plants and forecasting of crop yields. Method does not require prolonged observations and controlling of soil temperature during plant growing periods.

EFFECT: increased efficiency, elimination of employment of expensive bulky equipment for performing forecasting process.

5 dwg, 4 tbl