Biological peculiarities in the responsiveness of vegetable crop rotation to precision fertilization

Spatial and temporal variability of growing conditions which affects the production process management is characteristic of agrophytocenosis. Spatial heterogeneity of soil essential properties is widely reported. A precision fertilization should be effective tool to control crop productivity. The highest potential of such fertilization could be expected for vegetable crops in the favorable soil and climatic conditions of the Nechernozemie of North-West Russia. In a microvegetation stationary two-factor experiment, plastic bottom-less pots of 1 m2 area were used to artificially form the upper part of the soil profile (Aarable 0-22 cm and А2В 22-40 cm horizons) simulating natural lithogenic mosaics of agro sod-podzolic sandy, sandy loam, light loam and medium loam soils subjected to weak and good cultivation. Their minimum, maximum, and average parameters for the 0-22 cm horizon were as follows: рНKCl of 4.34-6.35 and 5.40, humus content (by Tyurin) of 0.92-2.50 and 1.72 %, labile phosphorus and potassium (according to Kirsanov) of 125-550 and 390 mg/kg and 22-400 and 209 mg/kg, respectively. The vegetable crop rotation included black radish ( Raphanus sativus L.)-potato ( Solanum tuberosum L.)-beetroot ( Beta vulgaris L.)-cabbage ( Brassica oleracea L.)-carrot ( Daucus sativus L.). For a comparison, we used different system of fertilization, i.e. control (no fertilizers); zonal system (ZS); precision fertilization 1 (PF-1); precision fertilization 2 (PF-2). In the ZS providing for a uniform application of the fertilizers based on the average soil properties, we used lime (4.5 t/ha + N95Р20К125) for black radish; manure (45 t/ha) + N100Р30К90 for potatoes; N130Р50К150 for beetroot; lime (2.1 t/ha) + manure (50 t/ha) + N120Р10К90 for cabbage; and N100Р40К130 for carrot. In the PF-1, two months before the radish was sown a precision soil cultivation has been performed using lime at 0-20 and 6.6 t/ha, peat at 0-900 and 390 t/ha; phosphorite flour at 0-750 and 94 kg/ha; potassium sulfate at 0-1710 and 407 kg/ha (as min-max and average). Further application of organic and mineral fertilizers before sowing (planting) was uniform, i.e. N70К60 for black radish; manure (45 t/ha) + N80К100 for potatoes; N100Р30К130 for beetroot; manure (50 t/ha) + N100Р10К70 for carrot; N100Р10К120 for white cabbage. In PF-2 providing average doses of all fertilizers equal to these in ZS, but differentiated for each pot based on actual soil parameters, we used lime (0-12 t/ha) + N70-120Р0-90К60-200 for black radish; manure (30-65 t/ha) + N80-110Р0-110К70-150 for potato; N90-170Р0-150К80-240 for beetroot; lime (2.1 t/ha) + manure (30-70 t/ha) + N110-135Р0-60 К40-120 for cabbage; N85-115Р10-90К79-180 for carrot. The experiments were arranged in four replications. In a field experiment the precision fertilization provided an increase in the productivity of vegetable crop rotation of 22.3 and 43.5 t/ha in control and ZS, respectively, to 47.9-49.4 t/ha. PF-1 and PF-2 resulted in the Сv reduction from 32 % and 16 % in the control and ZS to 9 %, and in an increased natural profitability of fertilizers by 21-49 %. A responsiveness of vegetable crop rotation to precision fertilization depended on biological features, the specific farming techniques and soil conditions. A decreasing responsiveness was as follows: black radish > car-rot » beet > potatoes > cabbage. A uniform application of high doses of organic fertilizers was the factor reducing