Strategies to Improve the Use Efficiency of Mineral Fertilizer Nitrogen Applied to Winter Wheat

Abstract

Recovery of fertilizer nitrogen (N) applied to winter wheat crops at tillering in spring is lower than that of N applied at later growth stages because of higher losses and immobilization of N. Two strategies to reduce early N losses and N immobilization and to increase N availability for winter wheat, which should result in an improved N use efficiency (= higher N uptake and/or increased yield per unit fertilizer N), were evaluated. First, 16 winter wheat trials (eight sites in each of 1996 and 1997) were conducted to investigate the effects of reduced and increased N application rates at tillering and stem elongation, respectively, on yield and N uptake of grain. In treatment 90‐70‐60 (90 kg N ha−1 at tillering, 70 kg N ha−1 at stem elongation and 60 kg N ha−1 at ear emergence), the average values for grain yield and grain N removal were up to 3.1 and 5.0 % higher than in treatment 120‐40‐60, reflecting conventional fertilizer practice. Higher grain N removal for the treatment with reduced N rates at tillering, 90‐70‐60, was attributed to lower N immobilization (and N losses), which increased fertilizer N availability. Secondly, as microorganisms prefer NH4+ to NO3− for N immobilization, higher net N immobilization would be expected after application of the ammonium‐N form. In a pot experiment, net N immobilization was higher and dry matter yields and crop N contents at harvest were lower with ammonium (ammonium sulphate + nitrification inhibitor Dicyandiamide) than with nitrate (calcium nitrate) nutrition. Five field trials were then conducted to compare calcium nitrate (CN) and calcium ammonium nitrate (CAN) nutrition at tillering, followed by two CAN applications for both treatments. At harvest, crop N and grain yield were higher in the CN than in the CAN treatment at each N supply level. In conclusion, fertilizer N use efficiency in winter wheat can be improved if N availability to the crops is increased as a result of reduced N immobilization (and N losses) early in the growth period. N application systems could be modified towards strategies with lower N applications at tillering compensated by higher N dressing applications later. An additional advantage is expected to result from use of nitrate‐N fertilizers at tillering.

Optimising nitrogen in order to improve the efficiency, eco-physiology, yield and quality on one cultivar of durum wheat

“…Some studies have shown that, depending on the level of fertility of the initial soil, split applications of N fertiliser result in higher rates of plant recovery and higher grain yields than under single applications (Mahler et al, 1994;Stockdale et al, 1997;Recous and Machet, 1998;Borghi, 2000;Blankenau et al, 2002).…”

Effect of nitrogen fertilizer application timing on nitrogen use efficiency and grain yield of winter wheat in Ireland

“…This indicates that making the first application of N to a winter wheat crop too early, while the crop can still acquire adequate N from soil reserves, could lead to inefficient recovery of that fertilizer N by the crop. A number of studies have found reduced recovery of N applied at tillering compared to that applied later in the growth cycle (Recous et al, 1988;Limaux et al, 1999;Blankenau et al, restricted, delaying the initial N could cause yield reduction. The objectives of this work were: (a) to determine the effects of initiating fertilizer N application to winter wheat at different GSs on grain yield and NUE of the fertilizer N and (b) to determine whether plant population density or soil N supply potential influenced the stage at which the first N application should be applied.…”

Response of Grain Sorghum to Split Application of Nitrogen at Tanqua Abergelle Wereda, North Ethiopia

“…Proper nitrogen application time and rates are critical to meet crop needs and indicate considerable opportunities for improving nitrogen use efficiency [4]. The growth stage of crops at which fertilizer is applied determines the nitrogen use efficiency; however, the response can vary by genotype.…”

“…The efficiency of the applied nitrogen in satisfying the demand of the crop depends on the type of fertilizer, timing of application, crop sequence, the supply of residual and mineralized nitrogen and seasonal trends [4,6].…”