Effects of nitrogen and frequency of irrigation on the growth and yield of peanut

The experiment was conducted during the summer months of 2004 in the controlled environment facilities of the College of Agriculture, Isabela State University, Echague, Isabela. Generally, the study aimed to evaluate the effects of varying levels of fertilizer and irrigation frequencies on the growth and yielding ability of Pn 1 (Biyaya 10) peanut cultivar. The study was arranged in Split Plot design assigning frequencies of irrigation as the main plot and levels of fertilizer as the subplot. Main plot that composed of I1- Two irrigations, 10 days and 25 days after planning, I2- Three irrigations, 10, 25 and 40 days after planting, I3- Four irrigations 10, 25, 40 and 50 days after planting and I4- Farmer's Practice (six timed irrigation, Control) while subplots were F1- 0-0-0 kg NPK per hectare, F2- 20-0-0 kg NPK per hectare (Recommended Rate), F3- 30-30-30 kg NPK per hectare (General Recommendation) and F4- 40-0-0 kg NPK per hectare. Results of field experiment showed that peanut growth was strongly affected by irrigation frequencies and levels of fertilizer. The combined effect of the two factors increases the production of flowers but a positively weak correlation existed. As to the number of effective nodules, number of developed and undeveloped pods obtained a strong positive linear correlation. The higher shelling percentage was obtained by the plants irrigated two times and fertilized with F4- 40-0-0, F3- 30-30-30 and F2- 20-0-0 kg NPK per hectare. The t-value however was insignificant. There was a corresponding increase in the seed yield and harvest index as the number of irrigation increases. Based from the results of the study, two times irrigation combined with 20-0-0 kg NPK per hectare (I1, F2) is strongly recommended for peanut production under the same prevailing conditions obtaining a net profit of Php 42,206.60 per hectare or 139 percent return on investment.