Potato Response to Nitrogen Form and Nitrification Inhibitors

Abstract

Several previous experiments where nitrification inhibitors have been used with potato have resulted in yield and/or tuber quality reductions, especially when used in combination with all-ammonium fertilizer N sources. This experiment examined the effectiveness of inhibitors over a 3-year period when used with several N sources with varying ammonium-N contents, all applied at emergence on an irrigated loamy sand in central Wisconsin. In 3 of 6 siteyears, use of an inhibitor increased total tuber yield with one or more of the N sources. Inhibitor use also sometimes increased tuber N accumulation and apparent recovery of applied fertilizer N. However, in 4 of 6 site-years, inclusion of an inhibitor with all-ammonium fertilizer N decreased harvested U.S. No. 1 tubers. This decrease was primarily due to an increased proportion of off-shape cull tubers, likely in response to the aversion of potato to ammonium nutrition. While use of inhibitors may have some application for potato production on irrigated sandy soils, it is clear that when they are used, the N fertilizer should be a mixed ammonium/nitrate fertilizer source.Resumen Varios experimentos previos en los que inhibidores de nitrificación se han usado en papa, han resultado en reducción de rendimiento y/o calidad de tubérculo, especialmente cuando se han empleado en combinación con fuentes de fertilizantes de puro amonio. En este experimento se examinó la efectividad de inhibidores en un período de tres años cuando se usaron con varias fuentes de N de diferentes contenidos de N-amoniacal, todo aplicado a la emergencia en un suelo franco-arenoso de riego en la región central de Wisconsin. En 3 de 6 sitios-años, el uso de un inhibidor aumentó el rendimiento total de tubérculo con una o más de las fuentes de N. El uso del inhibidor también algunas veces aumentó la acumulación del N del tubérculo y la aparente recuperación del N del fertilizante aplicado. No obstante, en 4 de los 6 sitios-años, la incorporación de un inhibidor con un fertilizante de puro amonio disminuyó la cosecha de tubérculos U.S. No. 1. Esta disminución se debió primeramente a un aumento en la proporción de tubérculos deformados eliminados, posiblemente en respuesta a la aversión de la papa a la nutrición amoniacal. Mientras que el uso de inhibidores pudiera tener alguna aplicación para la producción de papa en suelos arenosos de riego, está claro que cuando se usen, el fertilizante nitrogenado deberá ser de una mezcla de fuentes amonio/nitrato.

Cassava (Manihot EsculentaCrantz) Yields, Soil Nitrous Oxide Emission, and Soil Nitrogen Transformation Affected by Nitrification Inhibitors in Loamy Sand Soil in Thailand

“…The higher soil NO 3 − -N due to applying NIs might have been attributable to a higher soil NH 4 + -N ( Figures 3A and 3B), when compared to the CF plot. Later on in the growing season, a reduction in soil NO 3 − -N through crop uptake, NO 3 − leaching, and denitrification might be reasons for the minimizing the NI effect on soil NO 3 − -N, as was observed in this study and in the investigation by Kelling, Wolkowski, and Ruark (2011) after 56-57 days of fertilizer application in a potato field. However, the NI effect on soil NO 3 − -N was variable, depending on climatic conditions (Zaman et al 2009) and N fertilizer, for example, the application rate (Martin et al 1997).…”

“…The studied NIs have a suppressive effect on soil nitrification, because (1) DCD inhibits cytochrome oxidase and decreases the oxidation of NH 4 + to NO 2 − (Di and Cameron 2002) and (2) neem oil contains meliacins that can reduce soil nitrifier activity (Kiran and Patra 2003;Kumar et al 2007 (Martin et al 1997;Kumar et al 2007;Matsushima, Choi, and Inubushi 2009). In a potato field, DCD was effective in slowing nitrification and the soil had a higher soil NH 4 + -N than the applied urea-NH 4 NO 3 with no DCD (Kelling, Wolkowski, and Ruark 2011). Furthermore, Wadman, Neeteson, and Wijnen (1993) found that in potato fields, the use of DCD with a slurry application in late autumn increased soil NH 4 + -N in the upper soil layer compared to that without DCD.…”

“…DCD inhibits the oxidation of NH 4 + to nitrite (NO 2 − ) (Di and Cameron 2002), and relevant studies have shown that DCD could slow down soil nitrification and reduce N 2 O emissions (Pathak and Nedwell 2001;Matsushima, Choi, and Inubushi 2009). Application of DCD to a tuber field crop such as potato has shown the inhibitory effect on nitrification by maintaining soil NH 4 + (Wadman, Neeteson, and Wijnen 1993;Martin et al 1997;Kelling, Wolkowski, and Ruark 2011) and, in some circumstances, increasing tuber yields (Frye et al 1989;Martin et al 1993;Kelling, Wolkowski, and Ruark 2011).…”

Potato Response to Nitrogen Sources and Rates in an Irrigated Sandy Soil

“…Kelling et al (2011) found similar specific gravity values when AN, liquid urea ammonium nitrate, and a 50:50 combination of urea and AS were applied, however Sanderson and White (1987) reported that specific gravity was lower with urea than AN. Contrary to our findings, other studies found a greater quantity of culls when a higher proportion of the N applied was in NH 4 than NO 3 form (Bundy et al, 1986; Kelling et al, 2011). This phenomenon was attributed to NH 4 –induced water stress since crops receiving NH 4 tend to exhibit reduced water uptake (Hendrickson et al, 1978).…”

“…It is well known that most plant species have a preference for NO 3 − than NH 4 + . Moreover, some studies showed that plants supplied with both NO 3 − and NH 4 + may be more productive than those supplied with either form alone (Cao and Tibbitts, 1993, 1998; Kelling et al, 2011). Hence, the overall greater plant N accumulation and ANR for AN than AS may be due in part to the presence of both forms on N supplied by AN.…”