Planting System Effect on Yield Response of Russet Norkotah to Irrigation and Nitrogen under High Intensity Sprinkler Irrigation

Abstract

Conversion of potato ridged-row planting systems to wide bed planting systems may increase water and nitrogen use efficiency in commercial irrigated potato production systems by reducing the amount of irrigation water and water applied nitrogen fertilizer bypassing the potato root zone. Wide bed planting systems consist of planting multiple rows on a wide bed with 20 to 35% higher plant population than found in conventional ridged-row planting systems. The objective of this study was to evaluate the effect planting system has on yield response of ‘Russet Norkotah’ potato to irrigation and nitrogen. Planting systems evaluated were (1) conventional ridged-row with dammer-diking; (2) 3.7 m wide bed with five potato rows spaced 66 cm between adjacent rows centered on the bed and; (3) 3.7 m wide bed with seven potato rows spaced 46 cm between adjacent rows. Six irrigation amounts, 50, 70, 85, 100, 115, and 130%, of estimated evapotranspiration after tuber initiation and four nitrogen rates, <20, 50, 100, and 150%, of conventional recommendations were applied to the three planting systems. Interactions between irrigation amounts and nitrogen rate were significant for total and U.S. No. 1 yield, irrigation water use efficiency, and gross return in one or both study years. Interactions between nitrogen rate and planting system were significant for total and U.S. No. 1 yield, irrigation water use efficiency and gross return in the first year of the study. Interactions between irrigation amount and planting system were not significant. In the first study year, total and U.S. No. 1 yields were significantly increased 12 and 19 percent, respectively, under the 7-row bed planting system compared to ridged-row planting system. Comparison of ridged-row planting system and 5-row bed planting system on 31 commercial potato fields in eastern Idaho representing a combined area of 2,800 ha over 5 years resulted in significantly higher total yield and irrigation water use efficiency with the bed planting system. The 5-row bed planting system averaged 6% higher total yield, 5% less water application and an 11% increase in irrigation water use efficiency. The results of this study demonstrate that under high intensity rate sprinkler irrigation in the soil and climatic conditions prevalent in eastern Idaho, bed planting systems provide viable production alternatives for irrigated potato production that may increase total yield, gross return, and irrigation water use efficiency.