Effect of phosphorus in grassland-based livestock feed production

Abstract

Results of researches carried out over the long period regarding the effect of phosphorus fertilizers on change of natural and artificial (sowed) grasslands in hilly-mountainous regions of Serbia are analyzed in this paper. It was concluded that without the phosphorus higher biological production can not be achieved. However, it is of great importance to realize correct ratio between this nutrient and nitrogen and potassium, not only in order to achieve better efficiency, but also more rational use of mentioned nutrients. This ratio depends on the type of the natural grassland or leguminous-grass mixture, focusing on the leguminous species, if they are present and in which proportion. If leguminous plants are present on natural grasslands, phosphorus fertilizers, with or without potassium contribute to the increase of their presence. Also, they induce increase of yield, however in the absolute value yields are not high. Higher quantities of phosphorus fertilizer affect the increase of yield, but only if leguminous plants are present in floristic composition. Different response of species from the Fabaceaea and Poaceae families is registered in double fertilizing combinations. On natural grasslands, treated with PK, yield is always lower if there are no leguminous plants present, and if they are present the yield is lowest on grasslands treated with NK. Also on artificial (sowed) grasslands, P and PK treatments stimulate the growth of leguminous components. If also nitrogen is introduced, especially in higher quantities (over 50 kgN/ha) leguminous plants are suppressed from the mixture. It is recommended in years when leguminous plants are present in projected quantities or more, to use PK or smaller quantities of N fertilizer, and when leguminous are absent to give advantage to the nitrogen. This is based on research results which demonstrate that in the first and second year higher yields of leguminous-grass mixtures are obtained on treatment with P80K80 than N80P80K80 (2,86 compared to 1,74 and 9,05 compared to 8,87 t/ha of dry mass).

Navedeni su brojni rezultati istraživanja uticaja fosfornih đubriva na florističke promene, botanički sastav i prinos prirodnih i sejanih travnjaka u brdsko-planinskom području Srbije.Prirodni travnjaci su floristički složene zajednice ali su im prinosi vrlo niski (1,8 t/ha livade i 0,5 t/ha pašnjaci). Fosforna đubriva sama ili u kombinaciji sa kalijumovim utiču na povećanje udela leguminoza ako ih ima u sastavu. U tom slučaju utiču i na povećanje prinosa. Đubrenje travno-leguminoznih smeša samo sa PK doprinosi povećanju udela leguminozne komponente. Zahvaljujući tome unošenje P80K80 u prve dve godine obezbeđuje veće prinose od primene N80P80K80. Dok u smeši ima leguminoza (>20%) preporučuje se PK đubrenje, a kada leguminoza nema ili su nestale iz smeše prednost se daje azotnom đubrivu.