GALIA PANAYOTOVA1, SVETLA KOSTADINOVA2, STELA ALEKSIEVA1, NINA SLAVOVA1 and CATERINA ALADZHOVA1
1 Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 St. Zagora, Bulgaria
2 Department of Agrochemistry and Soil Science, Faculty of Agronomy, Agricultural University, 4000 Plovdiv,Bulgaria
PANAYOTOVA, G., S. KOSTADINOVA, S. ALEKSIEVA, N. SLAVOVA and C. ALADZHOVA, 2018. Nitrogen and phosphorus balances as dependent on durum wheat fertilization. Bulg. J. Agric. Sci., 24 (Suppl. 1): 9–17
The nitrogen and phosphorus balance under the influence of fertilization on durum wheat Progress cultivar was determined in a long-term fertilizer experiment, carried out at the Field Crops Institute - Chirpan on a soil type Pellic Vertisols during the period 2011-2013. Phosphorus and combined NP fertilization in rates N0P0, P80, P120, P160, N120P80, N120P120, N120 and P160 were applied. It was found that P fertilization increased insignificantly the grain yield (11.6-24.3% above the unfertilized control), and after NP fertilization the yield increased by 115.9-128.6% compared to the control. The total biological yield (grain + straw) without N fertilization were nearly two times lower (5900-6687 kg.ha-1) than that with the NP system (11087-11797 kg.ha-1). At P fertilization the plants uptook from 61.4 to 70.4 kg N.ha-1, and at NP fertilization - 146.9-165.7 kg N.ha-1. At P120 the plants absorbed 41.0 kg P2O5.ha-1, and at N120P160 the uptake was the highest - 77.2 kg.ha-1. The nitrogen balance was negative with a deficiency of -26.9 to -45.7 kg.ha-1 fertilization with N120. At incorporation of straw in the soil the balance was from 6.6-17.7 kg.ha-1. At fertilization with 80, 120 and 160 kg P2O5.ha-1 the phosphorus balance was positive and the soil accumulated from 45.4 to 120.4 kg P2O5.ha-1, and at combined fertilization of phosphorus with N120 - from 11.4 to 82.8 kg P2O5.ha-1. When incorporating straw in the soil at NP fertilization significant amounts of available phosphates were accumulated - 41.1-117.5 kg P2O5.ha-1.