Yields and Response of Cereal Crops to Phosphorus Fertilization under Changing Rainfall Conditions1
- A. E. Matar2
Response of cereal crops to N and P fertilization, grown under the semi-arid conditions of southern Syria, has been variable and somewhat related to climatic conditions. Two long-term fertilizer experiments were initiated in 1966 at Ezraa Experimental station, to study some of the P fertilization problems. The first studied interactions between fertilizer use and crop rotation and the second studied direct and residual effects of P on yields of wheat (Triticum aestivum L.) and lentil (Lens esculenta). Response to P depended upon climatic conditions. Data for 1966 to 1972 were used to correlate yields of wheat and lentil or the relative response to P fertilization with rainfall in each month of the growing season or the total of 2 or more months during the respective period. The following results were obtained: (a) A high positive correlation between yields of lentil and amount of rainfall in December (r = +0.90) March (r = +0.80) and that of wheat with total rainfall in December and January (r = +0.97) was observed. Early predictions of yields should be of great importance to agricultural planning under dry land farming conditions. (b) The relative response of either wheat or lentil to addition of P fertilizers was largely dependent on rainfall distribution. The correlation coefficient (r) between crop response to P and rainfall distribution was opposite in signs to that observed between yields of crops and rainfall distribution. A negative linear relation was found between relative response of lentil to P an amount of rainfall in December (r = −0.89) or March (r = −0.72). The coefficient of correlation between response of wheat to P and amount of rainfall in December and January was −0.95). In general, greater response to P fertilization was found in the dry and unproductive years, and a negative linear relationship was found between the relative response to P and the absolute yields of wheat or lentil (r = −0.98). It is postulated that P improved cereal crops' tolerance to aridity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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