Колообіг біомаси й елементів живлення у посівах сої залежно від попередника й основного обробітку ґрунту

Abstract

The article analyzes the main laws of the biological cycle of soybean plant biomass, and the parameters of recirculation of nutrients depending on the method and depth of the primary tillage and various preceding crops. It was found that the share of biomass alienated from the field with soybean harvest, depending on the various preceding crops and the primary tillage varied from 31,6 to 32,8 %, which in absolute terms ranged from 1,93 to 3,25 t/ha, and received to the soil with plant residues: from 3,97 to 6,67 t/ha or from 67,2 to 68,4 %. The largest amount of nutrients from 310,2 to 420,5 kg/ha of NPK is involved in soybean crops placed after cereals (winter wheat and spring barley) in the variant of cultivated without soil tillage by 20-22 cm (chisel-deep-tiller), and the lowest after corn for grain from 251,1 to 302,9 kg / ha NPK obtained in the variant during plowing by 20-22 cm. The largest share in the total amount of nutrients in soybean biomass belongs to nitrogen from 61,6 to 65,3 %, the share of phosphorus varies from 12,4 to 14,4 %, and potassium from 20,3 to 25,7 %. The amount of nutrients returned to the soil with plant residues, in relation to their content in the biomass ranges from 41.7 to 55.4% nitrogen, 11,1-14,7 phosphorus and 30,0-46,9 % potassium. It was found that the largest amount of nitrogen enters the soil with crop residues in the variant of soybean placement after soybean and main tillage (disc harrow) by 12-14 cm – 55,4 %. The share of phosphorus was 14,7 %, potassium – 29,8 %. When growing soybeans after cereals, corn for grain and sunflower, the intake of nitrogen in the soil with plant residues was 41,7-42,8 %, phosphorus 11,1-11,2 %, potassium 45,8-46,9 %. The lowest percentage of nitrogen removal - 69.5-69.6% was for the placement of soybeans after soybeans. Although for the removal of phosphorus (14,3%) and potassium – (16,1%) the option of placing soybeans after cereals, corn and sunflower prevailed, where these indicators were respectively (13,0-13,1 %) and (14,5- 14,7 %).