The evaluation results on the sunflower productivity in long-term experiences cultivated on the leached (cambic) chernozem according to the fertilization level and agrometeorological conditions of the 2011-2019 years are presented. The humus content in the arable layer of chernozem constitutes 3.4%; pHH2O = 6.8; ∑Ca + Mg = 37.4 meq 100g -1 of soil; texture clayey-loamy. Research in Moldova has shown that the average multiannual rainfall ensures obtaining of 2.7 t ha-1 of sunflower seed. From account of the soil natural fertility the 1.4 tons of sunflower seeds can be obtained. The untapped value of sunflower seed production under soil humidity conditions is 1.3 t ha-1. Crop rotation: wheat, corn, sunflower, barley, rape and legumes (alfalfa, peas, beans, soybeans). Investigations were carried out on the mineral nutrition levels: mobile phosphorus in the soil - 1.0; 1.5; 2.0; 2.5; 3.0; 3.5; 4.0; 4.5 mg 100g-1 of soil; exchangeable potassium in the soil - 29-32 mg 100g-1 of soil (Macighin method). Nitrogen doses were applied annually in doses - 0, 30, 45, 60, 75 and 90 kg ha-1. Sunflower seed production obtained from the control variant (unfertilized) with natural background (P1.0-1.2K29-30) ranged from 0.85 t ha-1 to 1.93 t ha-1. Administration of the mineral fertilizers on the natural background on average for 6 years led to the increase of the sunflower yields from 1.49 t ha-1 to 2.55 t ha-1, the production increase by 18-71%. On the phosphorus levels the crop yield increased from 18% containing 1.5 mg to 52% - 3.0-3.5 mg 100g-1 of mobile phosphorus in soil versus the background level N45K30 mg 100 g-1 of soil. On the P3.5K30 (PK) variant, the increase in yield versus of control variant was 38%. In nitrogen-based versions of PK at doses of 30-90 kg ha-1 the increase in sunflower production was 53-70% compared to the control variant and 15-32% relative to PK variant. The optimal soil phosphorus level for leached chernozem in the sunflower cultivation was 3.0-3.5 mg 100g-1 of soil (Macighin method), and optimal nitrogen level - 45-60 kg ha-1.

Chernozem leached, Fertilization, Nutrition level, Productivity, Sunflower.

sciences soil

Presentation: poster