Influence Of Tillage And Mineral Fertilizers On Soil Biological Activity Under Sweet Corn Crops

Abstract

P. V. Lykhovyd, S. O. Lavrenko

The article is devoted to study of the biological activity of soil under sweet corn crops depending on tillage depth, mineral fertilizers application rate with drip irrigation in the soil-ecological conditions of the Dry Steppe Zone of Ukraine. The plan of the experiment foresaw study of such factors: A — tillage depth (moldboard plowing on 20-22 and 28-30 cm); B — mineral fertilizers application rate (no fertilizers, N60P60, N120P120); C — plants density (35, 50, 65, 80 plants ha-1). We used water of the Ingulets irrigation system for irrigation. The water belongs to II quality class by agronomical criteria of the DSTU 2730-94 and its suitability for irrigation is limited. We studied the soil biological activity on variants with 65 plants ha-1 by the indicies of its respiration rate (method of V.I. Shtatnov) and linen decomposition degree (“application” method). At the same time we have made monitoring of the soil meliorative state depending on the moldboard plowing depth by the toxic salts content, anionic-cationic composition of the aqueous soil extract. The results of the laboratory-field experiments prove that the moldboard plowing depth , mineral fertilizers application rates and soil meliorative state have an influence on its biological activity. The maximum respiration rate, which is used to characterize an activity of the aerobic microflora of the upper soil layers, was at moldboard plowing on depth of 20-22 cm at non-fertilized experimental variant — 250.0 mg ???2/m2×hour. Increase of the tillage depth and mineral fertilizers application rate significantly decreased carbonic acid emission to the athmosphere, which was the minimum of 178.3 mg ???2/m2×h. The maximum linen decomposition degree, which is used to characterize an activity of the cellulose-decomposing soil microflora, was at moldboard plowing depth of 28-30 cm at non-fertilized experimental variant — 58.3%. The tillage depth changed cellulose-decomposing soil microflora activity insignificantly. Mineral fertilizers application at the maximum rate of N120P120decreased cellulose-decomposing soil biota activity 1.7 times comparatively to non-fertilized variant. Higher toxic salts concentration (at 0.006-0.019 %), sodium ions content (at 0.15-0.38 mg-eq/100 g of soil) in the 0-50 cm layer led to decrease of the soil biological activity. We consider, that the best from the agroecological point of view is the variant with moldboard plowing depth of 28-30 cm, mineral fertilizers application rate N120P120.

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