Author
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Alva, Ashok |
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Submitted to: Journal of Vegetable Crop Production
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/1/2004 Publication Date: 6/1/2004 Citation: Alva, A.K. 2004. Effects of pre-plant and in-season nitrogen management practices on tuber yield and quality of two potato cultivars. Journal of Vegetable Crop Production. 10: 43-60. Interpretive Summary: Nitrogen (N) is an important nutrient for crop production to attain maximum yield and quality of crop products. The end product of chemical transformation of any form of N fertilizer is nitrate form. This is an anion, poorly retained in the soil, moves readily with water front in the soil. In sandy soils downward transport of nitrate is rapid. When nitrate is transported down the soil profile below the rooting depth, it cannot be utilized by the crop, thus, is subject to continuous downward transport until it is reached to groundwater. Excess nitrate in groundwater is an environmental concern since concentrations of nitrate-nitrogen in excess of 10 mg/l is unacceptable for drinking water standards. Improved N management of potatoes is important for making the best use of N fertilizers for production of high quality tubers, and to avoid the negative impacts on the water quality. Three years field experiments were conducted for Ranger Russet and Umatilla Russet cultivars to investigate the effects of different rates of pre-plant N (56, 112, or 168 kg/ha) and frequencies of in-season N applications (2, 3, 5, 10, and 20) with a total of 336 or 448 kg/ha N for the entire growing period. This study showed no beneficial effects of increasing N application in excess of 336 kg/ha. The most optimal N management for potatoes in the Columbia Basin production region is 56 kg N/ha as pre-plant application with the rest applied in 3 to 5 fertigations 3 weeks after the seedling emergence. Technical Abstract: A good balance in pre-plant and in-season nitrogen (N) application is important for optimal production of high quality potato tubers in coarse texture soils, to improve N uptake efficiency, and minimize N losses. In this paper, we have summarized three years of field experiments conducted in a Quincy fine sand (mixed, mesic Xeric Torripsamments) in the Columbia Basin region in the Pacific Northwest (PNW) under center pivot irrigation. In the first year (2000), 'Russet Burbank' and 'Umatilla Russet' cultivars were grown with 112 kg N/ha as pre-plant soil application. In-season fertigation was done with 224 kg N/ha in either 2, 5, 10, or 20 doses starting three weeks after emergence. Total tuber yield was close to 60 Mg/ha in both cultivars. In-season N frequency had no significant effects on the tuber yield or quality of both the cultivars. The second year (2001) 'Ranger Russet' and 'Umatilla Russet' cultivars were grown with either 56, 112, or 168 kg/ha pre-plant N treatment (including the soil residual N content). The total N over the entire growing period was 336 kg/ha across all pre-plant N treatments. An additional treatment of 448 kg/ha total N was also evaluated with 112 kg/ha pre-plant N. Within these four main treatments, sub-treatments comprised application of in-season N fertigations at either 2, 3, or 5 frequencies starting three weeks after emergence. The tuber yields of both cultivars were not significantly influenced by either different pre-plant N rates (56 to 168 kg/ha) or total N rates (336 to 448 kg/ha). This study was repeated the third year (2002), except in-season N fertigation was evaluated at either 5 or 10 frequencies. The results of these studies demonstrated that N application in excess of 336 kg/ha rate failed to show any beneficial effects in terms of total tuber yields, or yields of different size grade tubers. Tuber specific gravity was also not significantly influenced by the different pre-plant N rates or total N rates. In-season N application through the irrigation system is a convenient method of fertilizer delivery without an added cost of application. Application of most of the N by fertigation during in-season with only about 56 kg/ha N as pre-plant appears to be the best management practice for production of high yields of good quality tubers in the Pacific Northwest production conditions. |
