The effect of granular fertilizer N-form, placement, and time of application on yield and quality of no-till winter wheat

Non-Peer ReviewedThe introduction of a practical snow management system, which utilizes no-till seeding into standing stubble immediately after harvest of the previous crop ("stubbling-in") has allowed for expansion of the North American winter wheat (Triticum aestivum L.) production area to include most of the western Canadian prairies. Soil nitrogen (N) deficiencies are usually associated with this production system and N fertilization is normally required to maximize grain yield and maintain acceptable grain quality. The present study summarizes twenty-one broadcast ammonium nitrate fertilizer field trials conducted from 1976 to 1986 in Saskatchewan with the objectives of determining the effect of date of N fertilizer application on grain yield, grain protein yield and grain protein concentration of stubbled-in hard red winter wheat. Dates of N application considered were early fall, late fall, early spring and late spring. Date of N application had significant influence on total grain yield, grain protein yield and grain protein concentration in 33, 33 and 29 % of the trials, respectively. Reduced grain and grain protein yields, attributed primarily to denitrification losses, and immobilization, were observed with fall N applications in four trials located in the northeastern part of the agriculture region of Saskatchewan. Reductions in grain protein concentration accompanied these N losses. In contrast, a prolonged dry period, following spring N applications resulted in a temporary stranding of fertilizer N on the soil surface at one location thereby delaying its availability to the plant until after early spring N deficiencies had seriously limited the yield potential of the crop. Delays in N application had the same effect. Reduced grain and grain protein yield and increased grain protein concentration were also observed for fall and early spring N applications in trials that experienced spring environmental conditions favorable to plant growth followed by prolonged drought. This sequence of environmental conditions resulted in maximum grain protein concentrations that ranged from 14.5 to 20 % compared to approximately 13 % under normal growing conditions for this region. An additional nine field trials were conducted from 1982 to 1986 with the objectives of determining the influence of fertilizer formulation and placement method on N response of stubbled-in winter wheat. Reduced grain and grain protein yield responses indicated large N losses due to volatilization of broadcast urea in three of the nine trials. Comparison with yield response curves for ammonium nitrate indicated that the losses with broadcast urea could be in excess of 50 % of the added N. Fall banding prior to seeding was effective in reducing losses with urea, but did not outperform broadcast ammonium nitrate applied at the same time. Yield losses, which were probably due to denitrification, were observed for both urea and ammonium nitrate broadcast in the late fall at one location

Prostaglandin I2 and the renin-angiotensin system

SIGLEAvailable from British Library Document Supply Centre- DSC:D51923/84 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Nitrogen fertilization for maximum economic yield of stubbled-in winter wheat

Non-Peer Reviewe

Estimating the effect of management on landscape yields

Non-Peer Reviewe

A comparison of no-till winter wheat response to seed-placed and broadcast nitrogen fertilizer placement

Non-Peer ReviewedWinter wheat (Triticum aestivum L.) can be successfully overwintered in most regions of the Canadian prairies if it is no-till sown into standing stubble immediately after harvest of the previous crop. Soil nitrogen (N) is usually deficient in this production system and N fertilization is necessary to optimize yield and maintain minimum quality standards. In the present study, the effect of seed-placed (SP) , early spring broadcast (BC), and SP+BC combinations of ammonium nitrate fertilizer (AN) on winter survival, grain yield, and protein production of winter wheat was investigated in 15 field trials conducted over a wide range of soil types and environmental conditions in Saskatchewan. Ammonium nitrate fertilizer placed in a 20 mm wide band with "Norstar" winter wheat seed produced average grain yield-N responses for 67 and 101 kg N ha-1 treatments that were only 86 and 70 % of comparable BC treatments, respectively. Average grain protein yleld-N responses for the 67 and 101 kg ha-1 SP N treatments were 86 and 73 % of comparable BC treatments, respectively. Changes in grain protein concentration due to increased rate of SP N were small. Similar grain and grain protein yield responses for 34 kg N ha-1 SP and BC treatments indicated that AN could be seed placed at low rates without reduced N-use efficiency. However, significant reductions in winter survival potential in all trials where differential winter-kill occurred suggested that even rates as low as 34 kg N ha-1 SP AN should be avoided when cultivars with marginal winter hardiness are utilized

Theory for Magnetism and Triplet Superconductivity in LiFeAs

Superconducting pnictides are widely found to feature spin-singlet pairing in the vicinity of an antiferromagnetic phase, for which nesting between electron and hole Fermi surfaces is crucial. LiFeAs differs from the other pnictides by (i) poor nesting properties and (ii) unusually shallow hole pockets. Investigating magnetic and pairing instabilities in an electronic model that incorporates these differences, we find antiferromagnetic order to be absent. Instead we observe almost ferromagnetic fluctuations which drive an instability toward spin-triplet p-wave superconductivity.Comment: Published versio

Importance of granular nitrogen fertilizer applicator selection and adjustment when fertilizing for maximum economic yield of no-till winter wheat

Non-Peer Reviewe

Optimizing nitrogen fertilizer response by winter wheat and rye

Non-Peer ReviewedSouthwestern Alberta has been the traditional winter wheat production area in western Canada. In recent years, the adoption of a practical snow management system, which utilizes no-till seeding into standing stubble immediately after harvest of the previous crop, has resulted in an extension of this production area to include most of the western Canadian prairies. Winter rye is also adapted to the no-till production system developed for winter wheat. Most stubble fields are deficient in available soil nitrogen (N) with the result that N fertilizer is a major input cost in the production of no-till winter wheat and rye. This report summarizes the N response observed in 40 winter wheat and 20 winter rye trials representing a broad range of soil types and environments in western Canada. Nitrogen fertilizer did not have a significant influence on heading date, maturity, hectoliter weight or kernel size in most trials. Where a significant N response was detected, maximum differences were a one and two day delay in heading, a two and nine day delay in maturity, a three and three kg reduction in hectoliter weight, and a seven and nine mg reduction in seed size for wheat and rye, respectively. A significant N response was observed more frequently for height. In this instance, the response was not directional and increases up to 25 and eight cm and reductions to nine and nine cm were observed with increased N for wheat and rye, respectively. The Gompertz equation provided the most complete description of the relationship between protein concentration and total plant-available N. Predicted grain protein concentration from this equation explained 98 and 93 percent of the variability in actual grain protein concentration for wheat and rye, respectively. The N response curves for protein concentration were similar for winter wheat and rye. After an initial lag, protein concentration increased rapidly, and then tailed off at high N levels. An inverse polynomial function was employed to describe grain and protein yield response to N fertilizer. Predicted yields from these equations explained 96 and 88 percent of the variability in actual grain yield and 94 and 89 percent of the variability in actual protein yield for wheat and rye, respectively. Winter rye demonstrated a greater N use efficiency and yield potential than winter wheat. There was a large interdependence of N response and environmental conditions, especially moisture supply, in determining yield in these trials