Effects of irrigation on yield and composition of principal elements of nutrients in maize-growing soil

Abstract

Extensive organic production under irrigation conditions requires greater amounts of NPK fertilisers. Furthermore, the mobility of fertilisers, especially of nitrogen, is greater under the increased soil moisture content, hence the incorporation of unnecessary amounts leads to nitrogen leaching into deeper layers causing pollution of the agro ecosystem. The objective of the present study was to determine maize yields and the content of NPK in soil under irrigation conditions after three years of the application of the same fertiliser amounts. There were four variants of water regime in the trail and the following amounts of fertilisers were incorporated: 136 kg N ha-1, 68 kg P2O5 ha-1 and 68 kg K2O ha-1. The obtained results show that the greatest differences in the content of the available soil nitrogen were established in relation to the rainfed regime. Moreover, under rainfed conditions, the highest nitrogen content (9.84 mg kg-1) and the lowest yield (10.2 t ha-1) were recorded at the end of the performed experiment. The lowest nitrogen content in the soil (7.84 mg kg-1) was established in the variant in which soil moisture had been maintained at the level 70-75% of filed water capacity (FWC). At the same time the average yield in this variant amounted to 13.55 t ha-1. The higher moisture was (80-85% FWC) the higher maize yield was (15.08 t ha-1), but also the nitrogen mobility over a profile depth was, and a greater holding capacity of nitrite in the humus horizon was. In comparison with rainfed conditions, irrigation variants had lower contents of P2O5 and K2O in the soil, which is, among other things, a consequence of higher yields obtained under irrigation conditions.

Cilj rada bio je da se u irigacionom vodnom režimu utvrde prinosi kukuruza i sadržaj NPK hraniva u zemljištu nakon tri godine primene iste količine đubriva. Rezultati pokazuju da su najveće razlike u sadržaju pristupačnog azota u zemljištu utvrđene u odnosu na prirodni vodni režim, koji je na kraju izvođenja ogleda bio sa najvećim sadržajem azota (9,84 mg·kg-1) i sa najmanjim prosečnim prinosom (10,2 t·ha-1). Najmanji sadržaj azota u zemljištu bio je u varijanti održavanja zemljišne vlage na nivou 70-75% PVK (7,84 mg·kg-1) na kojoj je dobijen prosek prinosa 13,55 t·ha-1. U uslovima prisustva veće količine vode (80-85% PVK) bila je najveća rodnost kukuruza (15,08 t·ha-1), ali i veća pokretljivost azota po dubini profila, kao i zadržavanje nitrata u humusnom horizontu. U poređenju sa prirodnim vodnim režimom, varijante sa navodnjavanjem su imale manji sadržaj P2O5 i K2O u zemljištu što je, između ostalog, zbog ostvarenih većih prinosa u navodnjavanju.