Nitrogen and phosphorus fertilizers for wheat and barley in a semi-arid region

Abstract

SUMMARYNineteen NP experiments were carried out with wheat and barley mostly in the Mesaoria plain of Cyprus over the period 1968–78. The fields were fallowed over the season preceding the experiments. Rainfall ranged from 68 to 405 mm. Kyperounda, a tall durum wheat, Pitic 62, a semi-dwarf aestivum wheat, and Athenais barley were the test varieties. No yield was obtained when rainfall was below 100 mm. Athenais barley consistently outyielded the wheat varieties, particularly Kyperounda, by up to 200% presumably because of earlier heading, which helpedthe crop to escape drought to a certain extent.Kyperounda wheat and Athenais barley mostly responded to 35 kg N/ha but Pitic 62 benefited from up to 70 kg N/ha. Fertilizer N not taken up in a year of extremely low rainfall remained in the soil and was available to the following crop.Response to P was more marked when rainfall was below 250 mm being linear over the rates tested (highest rate 26 kg P/ha). Athenais barley responded to P more than the other varieties. Bicarbonate-soluble soil P was between 1 and 10 mg/kg.Since rainfall is unpredictable it is recommended that 20–40 kg N/ha be applied atseeding together with 13–26 kg P/ha. A similar amount of N should be top dressed in late January. The higher amount refers to the semi-dwarf Pitic 62 wheat and could be increased further if the December-January rainfall, which normally constitutes 40% of the total, is high. These rates refer to crops grown after fallow. For continuous growing the rates would probably have to be increased.

Soil and Fertilizer Phosphorus and Crop Responses in the Dryland Mediterranean Zone

“…This coincided with results obtained in Jordan (Haddad, 1986a;1986b) on lentil and chickpea, and was similar to those obtained on wheat and barley (Harmsen et ai., 1983;Matar et ai., 1987;Orphanos, 1987;Krentos and Orphanos, 1979;Matar, 1977). The response of the pea crop to P application was more consistent than for other legume crops studied.…”

“…In all except extreme drought situations and where there was sufficient residual N from a previous legume (Abdel Monem et aI., 1990a), N is almost invariably deficient as exemplified by recent reports from countries ranging from Morocco (Ryan et aI., 1992) to Pakistan (Rice et aI., 1990). Though less frequent than N, deficiencies of P are widespread in all countries of the region, with both frequently occurring simultaneously (Michel et aI., 1967;Krentos and Orphanos, 1979;Loizides, 1970). Exceptions to this generalization can be largely traced to residual P build-up, which is discussed later.…”

“…Increases in the order of 0.5 to 1 ton of grain were generally obtained from application of from 13 to 18 kg P/ha. Most, if not all, soils of the region are calcareous, and naturally low in available P (Harmsen, 1983;Krentos and Orphanos, 1979;Matar, 1976a;Matar et aI., 1988aMatar et aI., , 1988cNCARTI. 1975NCARTI.…”

“…Several scientists in the W ANA region had observed relatively larger and more significant yield responses to P application in dry and unproductive years, and/or in shallow soils, while yield responses to N tend to be larger under high rainfall conditions (Harmsen et aI" 1983;Krentos and Orphanos, 1979). At the wetter sites, there seemed to be little or no P response, even when the available soil P was in the low range.…”

“…6, 7). This positive P response in dry areas has been demonstrated on lentil, wheat, and barley in several countries of the region (Harmsen et ai., 1983;SoItanpour et ai., 1988;Krentos and Orphanos, 1979;Matar, 1977) and deserves to be considered seriously for increasing food and forage crops in the region. …”