Published in Scientific Papers. Series A. Agonomy., Vol. LVI
Written by Stefka TODOROVA, Krasimir TRENDAFILOV, Violeta VALCHEVA
Generally the stockpiling fertilization with phosphorus and potassium is applied before planting of perennial crops and requires introducing of high fertilization rates, calculated on the basis of the soil reserves and forecasted balance of the element for a long period. Opportunities for correction of stockpile fertilizer rates after planting of perennials are very limited, taking into account the technological limitations of incorportation of fertilizers to the depth of active root layer.This requires precise calculation of fertilizer rates, depending on the heterogeneity of the soil even before planting. Present work is an attempt for approximation of balanced stockpiling rates with phosphorus and potassium to the actual needs of plants of fertilization on the whole area of the plantation. It is used nearest neighbour method, combined with soil sampling in graticule conformed to the configuration of the area. The optimal density of the graticule is established experimentally by prior reconnaissance soil sampling and defining the function of the spatial heterogeneity expressed as variogram. Obtained on the first approximation results are generalized to the threshold of economically significant sensitivity to corresponding nutrient, and then are outlined sub-areas for differentiated fertilization. The advantages of the nearest neighbour method in the proposed model for geospatialization is that, its application provides an outlining of sub-areas for diferentiated fertilization with proper configuration which is suitable for service by fertilizer technique.
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