Nitrogen and potassium fertilization in no‐till hard red spring wheat production

Abstract

There is a need to develop more efficient nutrient management strategies to maximize wheat (Triticum aestivum L.) grain yields and increase grain protein levels. Urea, most widely used N fertilizer, is susceptible to substantial losses, resulting in low nitrogen use efficiency (NUE). This study assessed the effect of N and K fertilization on hard red spring wheat production under dryland no-till conditions in Montana. A field experiment was conducted during one growing season at two locations in Northcentral Montana. Fertilizer N was applied as urea (46-0-0) or as a urea-KCl (50:50 blend) at planting to achieve two target N rates, 135 and 270 kg N ha −1. Biomass weight, N content, and sensor-based Normalized Vegetative Difference Index (NDVI), yield, test weight, and grain protein content of wheat was evaluated. Results indicated that: (a) N may increase wheat grain quality (protein content) even when wheat yield is not increased, (b) KCl application, along with N, may result in greater wheat biomass production and grain protein values, and (c) NDVI may be more sensitive to the amount of produced biomass than to N content of that biomass. In conclusion, even if yield response to N is minimal, N is beneficial for improving grain protein content of wheat. Addition of KCl along with N may produce greater wheat biomass and increase biomass N content. The NDVI may be more sensitive to the amount of produced biomass than to its N content.

Spring wheat yield and grain quality response to nitrogen rate

“…In this study, across all site‐years, grain protein content increased with N rate. This agrees with findings by Walsh (2020), who reported that wheat grain protein content may be enhanced with N application even if grain yield is not increased. Several authors have also found a positive relationship between N rate and grain protein (Fiez et al., 1994; Kindred et al., 2008; Terman et al., 1969; Vaughan et al., 1990).…”

“…In general, across all site-years, NUE was lower at very high N rates of 252 and 336 kg N ha −1 . This is typical of NUE trends as observed by several authors (Dobermann, 2005;Walsh & Walsh, 2020). The reason for the decrease in NUE with increased N rates is associated with increased loss due to denitrification and leaching.…”

“…Zhang and Raun (2006) noted that other yield goals in areas like the Midwest were determined by averaging yields from the past 5 yr and adding 20%. Nitrogen-response trials and historical yields, however, are not always helpful in accurately estimating N (Walsh & Walsh, 2020). According to Raun et al (2001), the application requirement of a crop can be determined by combining the yield potential and soil test NO 3 -N for an estimate of the total N required.…”