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Title: Nitrogen Management for Maximizing Potato Yield, Tuber Quality, and Environmental Conservation

item Delgado, Jorge

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 4/18/2007
Publication Date: 2/2/2009
Citation: Essah, S., Delgado, J.A. 2009. Nitrogen Management for Maximizing Potato Yield, Tuber Quality, and Environmental Conservation. p. 317-325. E.K. Yanful (ed) Appropriate Technologies for Environmental Protection in the Developing World. Springer, The Netherlands.

Interpretive Summary: Our results clearly show that nitrogen management is key in maximizing potato yield and tuber quality. Our results are also unique in showing that over-application of initial N fertilizer not only reduced the agronomic efficiency increasing the potential for N losses to the environment, but can also contribute to lower total tuber yield and quality. These results show that farmers may be over-applying N fertilizer for this region and may be reducing their yields and lowering tuber quality. Our recommendation is that farmers develop a comprehensive N management plan including the accounting for other N sources such as initial soil NO3-N and NO3-N in background irrigation water and N cycling from cover crops. Our results agree with those from Errebhi et al. (1998a; 1998b) and Westermann and Kleinkopf (1985) which showed that larger preplant N applications can delay tuberization and reduce tuber quality. We found that N over-application can also affect tuber quality, especially if excessive N is applied during the growing season. We found a large range among varieties such as the 157 kg N ha-1 for Canela Russet (90 kg N ha-1 at planting with 67 kg N ha-1 applied during the growing season) vs the optimum 90 kg ha-1 for Sangre. These unique results need to be tested under commercial conditions to see if lower N application than the traditional practices will maximize yields and quality at a larger scale. Nitrogen management for potato is difficult since under- and/or over-application will reduce yields and quality.

Technical Abstract: We need to continue developing new management practices to reduce N losses that affect air, soil, and water quality. Two key components identified to increase N use efficiencies (NUE) are the use of varieties and better synchronization of applied N with N uptake (Delgado 2001). We monitored the effects of N-management on agronomic efficiencies of N fertilization for Sangre and Canela Russet potato (Solanum tuberosum L.)varieties grown during 2003 and 2004 in the San Luis Valley of Colorado. In this region, traditional farmer practices apply between 180 to 240 kg N fertilizer ha-1. Our unique results show that optimum N application for maximum total and marketable tuber yield for Canela Russet was 157 kg N ha-1 (90 and 67 kg N ha-1 applied at planting and during the growing season, respectively). Sangre maximum production and crop quality was observed with 90 kg N ha-1 applied at planting. Our results showed that tuber production and quality can be affected not only by low N availability, but also by N over-fertilization. Our unique paper shows that N over-fertilization not only increases the potential for N losses to the environment, it also lowered yields and reduced tuber quality. This study showed that with the optimum N rates and/or varieties we can reduce N inputs and increase NUE without reduction of yields while maximizing crop quality and potential economic return for farmers. We need to continue looking for the optimum rates that maximize yield and quality while avoiding low N inputs and over-fertilization.