Phosphate fertilization primes production of rangeland on brown rendzina soils in the Galilee, Israel

Abstract

Primary production on terra rossa and brown rendzina soils on the hills of the Galilee in Israel is severely restricted by nutrient, mainly phosphorus, deficiency. The purpose of this study was to investigate the residual effects of a single application of P fertilizer and the long-term role of P in the production and botanical composition of herbaceous vegetation. A fertilizer trial on brown rendzina soil (Lithic Haploxeroll) with P and N treatments was established and monitored for 6 years. Phosphate fertilization consisted of a single surface application of 45 or 90 kg P ha −1 as enriched superphosphate (25% P 2O 5). In the first year, yield of herbaceous vegetation in P fertilized plots increased fourfold compared with the control, and about two-fold during the following 5 years. In the sixth year, production in the fertilized plots diminished, but was still significantly higher than in the control plots. In addition, there was a large increase in the legume cover that improved the nutritional quality of the range vegetation. Concentration of P and N in the plants as well as total P and N uptake, increased significantly. Available P concentration in the soil increased two- to five-fold in the year after fertilizer application and a strong residual effect persisted for up to 5 years. A single application of P (45–90 kg ha −1) on brown rendzina soil in the Galilee raised the total 5-year primary production from 780 g m −2 dry matter in the control plots to 1840–2100 g m −2 dry matter in the fertilized plots. Forage quality was also improved for an extended period of over 5 years. Phosphate nutrition was shown to be the key to raising productivity of these soils. The long duration of the effect increases the chance that infrequent P fertilization on these rangelands will be economically feasible in certain conditions.