(328) Effect of Supplemental Nitrogen Applicationat Selected Times on Pecan
Supplemental nitrogen applications were tested to reduce irregular bearing and improve yield on drip-irrigated pecan (Caryaillinoinensis Wangenh. C. Koch. cv. Mohawk) trees planted in 1989. Treatments were: 1) no N fertilization; 2) 75 kg·ha-1 N in March; 3) 75 kg·ha-1 N in March plus 50 kg·ha-1 N in August; and 4) 75 kg·ha-1 N in March plus 50 kg·ha-1 N in October. Withholding N did not reduce July leaf N concentration compared to the other treatments until the sixth year of the study. Trees receiving N had similar July leaf N concentrations regardless of treatment throughout the study. October leaf N concentrations were unaffected by treatment, except in 2002, when withholding N suppressed leaf N compared to other treatments. The percentage of fruiting shoots was lower when supplemental N was applied in October compared to August during 2 of 6 years. Otherwise, the percentage of fruiting shoots was unaffected by treatment. Weight per nut and kernel percentage were not affected by treatment, except kernel percentage was lower during 1 year when supplemental N was applied in August compared to October. Kernel grade was usually not affected by treatment.