Wheat Variety Trial as Influenced by Previous Crop, Fertility, and Tillage
Crop variety testing plays an integral part of the research conducted at the Carrington Research Extension Center. Much of the varietal testing, however, is conducted under a conventional system consisting of conventional tillage with fertility levels to produce optimum yield. In 1997, a trial was initiated to evaluate the impact of nitrogen fertility rate (0 or 80 lbs/ac ammonium nitrate), a continuous cropping system (previous crop field pea), and tillage (conventional vs no-till since 1986) on grain yield and quality of hard red spring and durum wheat varieties.
Varieties within this trial, when analyzed across tillage and fertility, performed differently in respect to days to head, plant height, kernel weight, test weight, grain protein, and grain yield (data not presented). When evaluating the impact of tillage across varieties and fertility we observe no significant impact on wheat grain yield (p²0.05). However, varieties under the no-till system were significantly later at heading and produced a greater test weight as compared to conventional tillage system (Table 1). When evaluating the impact of fertility across variety and tillage, significant differences were observed with grain protein, grain yield (p² 0.07) and days to head (Table 2). The impact of fertility and variety caused an interaction related to these traits: days to head, test weight, kernel weight, and grain protein. This influence of variety and fertility did not impact grain yield and indicates that varieties performed similarly when grown after a legume with no additional N as when 80 lbs N/ac were applied to the legume ground.