Effect of rate and method of phosphate placement on productivity of durum wheat in mediterranean environments

Abstract

Cereals grown on calcareous soils in a dry Mediterranean climate have generally responded to P fertilizer. Broadcasting is the common practice used by most farmers.

The effects of rate and method of phosphate placement on dry matter production (TDM), grain yield and P uptake by durum wheat (Triticum vulgare L.) were investigated. Factorial experiments with four levels of P (0, 17.5, 35, and 52.5 kg P ha−1) and 2 methods of application (banding by drilling with the seeds, and broadcasting before surface tillage and sowing) were conducted for three consecutive seasons at three experimental sites: Breda (Typic Calciorthid, 281 mm); Tel Hadya (Chromoxeretic Rhodoxeralf, 328 mm) and Jindiress (Palexerollic Chromoxerert, 471 mm). Three levels of P were used in the third season only. Treatments were replicated in three blocks. The average values of NaHCO3-extractable P in the plow layer were 2.8, 3.7 and 2.1 mg P kg−1 at Breda, Tel Hadya, and Jindiress, respectively.

Above-ground total dry matter (TDM) was determined at tillering and anthesis. Grain and straw yields were estimated separately at harvest. The P concentration in plant material was determined at both stages. At tillering, TDM and total P uptake (TPU) increased linearly with the rate of P applied. It was found that (i) 17.5 kg P ha−1 banded was as effective in increasing TDM and TPU as 52.5 kg P ha−1 broadcast, and (ii) the average relative percentage increase in TDM at tillering due to P banded as compared to P broadcast was 54%, with significantly less response to banding, by maturity and harvest. The response to P placement was found to be site related. At Breda, banding was found superior to broadcasting in all 3 seasons with a relative increase in grain yields equivalent to 34, 63 and 23% in the 3 successive seasons, when optimum amounts of P were applied. However, in two out of three seasons only banding was found superior to broadcasting at both Tel Hadya and Jindiress.

As a result, banding P is recommended for durum wheat grown on the calcareous soils of the Mediterranean regions because it stimulates growth and P uptake early in the season and increases the crop potential for good grain and straw yields especially in dry areas. Given equal rates of P application, banding was found superior to broadcasting in most cases.