Nitrogen response characteristics of wheat protein in relation to yield responses and their interactions with phosphorus

1992 ◽  
Vol 43 (5) ◽  
pp. 969 ◽  
Author(s):  
ICR Holford ◽  
AD Doyle ◽  
CC Leckie

Wheat fertilizer experiments at 58 sites on the north-western slopes and plains of New South Wales clearly demonstrated a widespread and severe deficiency of nitrogen on many soils. The frequency (70%) and magnitude of responses to nitrogen were much greater than previously recorded. Nitrogen fertilizer required to achieve near-maximum yields was also much greater, with more than half the experiments requiring more than 30 kg N/ha and 23 experiments requiring more than 60 kg/ha. Deficiency of nitrogen for grain protein was almost universal with only two experiments failing to respond to nitrogen fertilizer. The yield response curves for all except three experiments were well fitted by the exponential (Mitscherlich) equation, but the majority of protein response curves were convex to the X axis, or linear, so that maximum protein concentrations could not be estimated. There were four distinct types of protein response curves, and their occurrence seemed to be related to the degree of nitrogen deficiency. Where nitrogen was most deficient (mean protein <10.5%), response curves were convex or linear; at intermediate deficiency (mean protein 11.7%), response curves were sigmoid, and at low deficiency (mean protein 13.4%), curves were exponential. Yield response rarely occurred where grain protein was greater than 12%. In 10 experiments with convex or sigmoid curves, the first increment of fertilizer depressed protein levels, due to the dilution effect of a large yield response. Increasing amounts of phosphorus fertilizer increased the response to nitrogen in nine experiments and in most of these the response curvature was correspondingly decreased, especially at the highest rate of phosphate. These interactions showed that nitrogen was the primary limiting factor in most of these experiments. P fertilizer tended to depress protein concentrations, especially in the absence of N fertilizer, but it had no consistent effect on protein response to N. Because of the dominance of convex protein response curves, much higher levels of fertilizer N were required to give maximum protein responses than were required to give maximum incremental yield responses. It was usually uneconomic therefore to use fertilizer solely to maximize protein increases.

1997 ◽  
Vol 48 (8) ◽  
pp. 1187 ◽  
Author(s):  
I. C. R. Holford ◽  
J. F. Holland ◽  
A. J. Good ◽  
C. Leckie

Sorghum fertiliser experiments at 40 sites on the north-western slopes andplains of New South Wales demonstrated that many soils are severely deficientin nitrogen (N), but most yield responses to fertiliser N occurred on sites inthe southern part of the region. Grain yields responded to fertiliser in fewerthan half of the experiments but protein concentrations responded in about75%.There were 4 distinct types of protein response curve, and the type of curvewas related to the degree of N deficiency. In the most deficient experiments(mean protein 6·1% or less), response curves were convex to thex -axis or linear; at intermediate deficiency (mean protein7·2%), response curves were sigmoid; and at low deficiency (meanprotein 9·7%), response curves were Mitscherlich. Yield responsenever occurred where grain protein was >10%.Maximum grain yield responses and amounts of fertiliser N for maximum profit,estimated by fitting the Mitscherlich equation to response curves, weresignificantly correlated with soil nitrate N levels at various depths in thesouthern experiments, but not in the northern experiments. This difference inN responses appeared to be caused by lower rainfall and higher soil N in mostof the northern experiments. Nitrate-N levels in soils sampled to 15 or 30 cmdepth were better correlated with yield response ( r> 0·81) and fertiliser requirement (r >0·72) than N levels to deeper depths.There was little or no fertiliser N recovery in the grain in the northern experiments but substantial recovery in the south where it was generallygreater than recovery by wheat in earlier experiments in the same region.Fertiliser requirement in relation to soil nitrate-N levels was lower thanthat of these wheat experiments. This was attributed to mid-spring soilsampling for sorghum which underestimates the soil N available to the sorghum


Author(s):  
S.D. Mcbride

Major findings from 13 pasture irrigation experiments conducted in Canterbury are discussed. Yields and response curves on 8 of the experimental sites were very similar to those of the long-term trial (34 years) site at the Winchmore Research Station. Irrigating when soil moisture dried to 50% asm (available soil moisture), increased annual pasture DM yields by an average of 5.2 t/ha DM (80% increase over the non-irrigated yield). Response per irrigation and yield variation between years decreased as the number of irrigations increased. During water restrictions, irrigators often choose to either keep watering their whole farm with a longer irrigation return period, or drop out paddocks and fully irrigate the remainder. The irrigation response data are used to discuss these and other possible strategies. Keywords: irrigation, pasture yields, response curves, water restrictions


1992 ◽  
Vol 32 (3) ◽  
pp. 383 ◽  
Author(s):  
AD Doyle ◽  
CC Leckie

Grain yield, protein, and nitrogen uptake responses are reported for 6 wheat fertiliser experiments in northern New South Wales which were representative of sites that were highly responsive, moderately responsive, and non-responsive to nitrogen (N) fertiliser applied at sowing. Apparent recoveries of applied N of 33-57% in the grain were recorded where grain yield was steeply increasing in response to additional applied N. Where yield increases were smaller in response to increments of N fertiliser, N recovery was 22-3096, but where further N application increased grain protein content but not grain yield, apparent recovery of additional fertiliser N fell below 20%. Apparent recovery was less than 10% in experiments where there was no yield response to N fertiliser. The implications for fertiliser recommendations are discussed relative to potential premium payment for wheat protein levels. It was concluded that established premium payments are too low to make N application an economic proposition to increase grain protein levels in the absence of grain yield responses.


1976 ◽  
Vol 86 (2) ◽  
pp. 373-377 ◽  
Author(s):  
M. R. J. Holmes ◽  
J. R. Devine ◽  
F. W. Dunnett

SummarySeven field experiments were made on the effect of two harvesting dates on the nitrogen requirements of sugar beet. All were on Rauceby series soils overlying oolitic limestone in Lincolnshire.Nitrogen fertilizer increased sugar yield in all experiments, and yield was considerably higher at the mid-December harvest than in early October. On average, the sugar-yield response to nitrogen was greater at the late harvest, and the requirement for nitrogen was about 45 kg/ha higher then than at the early harvest. Sugar content was depressed less at the late harvest than at the early by increasing nitrogen rate.These results suggest that farmers should apply more nitrogen to fields that they plan to harvest late than to early-harvested fields; they also have implications for the conduct and interpretation of nitrogen response experiments on sugar beet.


1970 ◽  
Vol 10 (45) ◽  
pp. 450 ◽  
Author(s):  
VF McClelland

The effect of nitrogen fertilizer on the yield and grain protein content of several cultivars of wheat grown under wheat-fallow and wheat-pasture-pasture-fallow rotations was studied in the Victorian Mallee during 1962 to 1965. Nitrogen fertilizer increased whest yield on the wheat-fallow rotation, but had little effect on the wheat-pasture-pasture-fallow rotation. Changes in grain protein content due to nitrogen fertilizer were small compared with changes due to the type of cropping rotation. Climate had relatively little influence on grain protein content despite marked variability in rainfall. The significance of this result is discussed in relation to a correlation established between grain protein content of unfertilized plots and yield response to applied nitrogen. The performance of the wheat cultivars Insignia, Olympic, and Beacon with and without applied nitrogen was similar under both rotations.


1979 ◽  
Vol 19 (99) ◽  
pp. 488 ◽  
Author(s):  
BS Dear ◽  
DJ McDonald ◽  
G Falconer

Egret wheat was sown into rice stubble using a minimum cultivation technique called seedavation. Nitrogen was surface applied as sulphate of ammonia in 1974 and ammonium nitrate in 1975 at 0,60 and 120 kg N ha-1. Phosphorus as single superphosphate was drilled with the seed at 0 and 17.5 kg P ha-1. The effects of burning, incorporating and removing rice stubble were compared. Large grain yield responses to nitrogen were achieved with yields up to 5 t ha-1 despite the use of minimum tillage. Tiller numbers were highly correlated with yield. No yield response to phosphorus was obtained. Low protein levels (less than 10%) suitable for biscuit wheat were obtained even at the high nitrogen fertilizer rates. The effect of stubble treatment varied between years; in 1974 it had no effect on yield; however, in 1975 removing or incorporating stubble reduced yields compared with burning the stubble. These results indicate that in rice growing areas a significant rise in wheat yields can be achieved through the use of higher nitrogen fertilizer rates.


1995 ◽  
Vol 75 (2) ◽  
pp. 381-386
Author(s):  
A. J. Leyshon ◽  
C. A. Campbell

Two nitrogen (N) fertilizer response trials were superimposed, in 2 consecutive years, on a set of large plots of irrigated bromegrass (Bromus inermis Leyss.) that had been fertilized with different rates of fertilizer N up to 200 kg ha−1 for the previous 9 and 10 yr, respectively. During those years, forage dry matter responded in direct proportion to fertilizer N rate. In the subsequent two trials we determined the residual effects of the prior fertilizer treatments on the response of bromegrass to new applications of N fertilizer, and the N rate required to achieve maximum yields. The yield response of the bromegrass to the applied N was a function of prior fertilizer history and the moisture conditions. In the first trial, under good moisture conditions, the previously unfertilized plots had maximum yields at a N rate of 382 kg N ha−1; yields declined at higher rates. Responses of previously fertilized plots to additional N were linear. The y-intercepts (where no N was applied) were higher for plots that had been fertilized at higher N rates in the initial 9-yr study while the slopes of the yield responses were less steep. In contrast, in the second trial, conducted in a year when irrigation water was restricted, all forage yield responses to N fertilizer were curvilinear, Y-intercepts were again higher on plots that had been fertilized at higher N rates in previous years. In this case, however, the slopes of the N responses became progressively steeper with increasing N rate while increasingly larger quadratic coefficients resulted in maximum yields being attained at progressively lower N rates. Nevertheless, maximum yields were higher than those of the previously unfertilized plots. Changes in the response curves were attributed to alterations in the soil organic N and to a lesser extent, to changes in the capability of the bromegrass to respond to fertilizer N. Soil tests found no carry-over of fertilizer N as residual inorganic N but the initial potential rate of mineralization (N0k) reflected changes in the quality of soil organic matter influencing the response to N fertilizer applications. The results suggest the need for soil testing laboratories to take into account the prior fertilizer history of the grass stand when developing recommended N fertilizer rates for irrigated bromegrass. Key words: Bromegrass, N fertilization, residual N, mineralizable N


1963 ◽  
Vol 3 (11) ◽  
pp. 300 ◽  
Author(s):  
EF Henzell ◽  
GB Stirk

Two field experiments were carried out at Samford during 1958, 1959, and 1960 using three grasses, nitrogen fertilizer, and supplementary irrigation. Attention was concentrated on grass growth during September to December, a period that is particularly important for livestock that have been grazed on poor quality feed during winter. Nitrogen deficiency was more important than soil moisture stress in limiting growth of grass under natural rainfall. Nitrogen fertilizer caused large increases in yield each year, and maximum yields above 10,000 lb of d y matter an acre were produced by uninterrupted growth up to December or January-four or five times the yields of the unertilized plots. Differences between the yields of the three grasses were small compared with the size of the nitrogen response. In the spring of 1960-61, which was the driest of the three seasons during this investigation, soil moisture stress reduced growth of nitrogen-fertilized Rhodes grass (Chloris gayana Kunth.) up to mid-December one-third. It was observed that fertilized Rhodes grass withdrew water more rapidly and to a greater depth than Rhodes grass without added nitrogen.


1974 ◽  
Vol 54 (1) ◽  
pp. 1-7 ◽  
Author(s):  
D. R. KNOTT

Six tests were run in 1970 and 1971 to measure the yield and protein response of five diverse wheat cultivars (Triticum aestivum L.) to fertilizer treatments and particularly to nitrogen. The results indicate that complex interactions occur between cultivars, locations, and fertilizer treatments. Of the five cultivars, Pitic 62 and Era showed little yield response to the treatments used but gave the largest increases in protein content. Inia 66 and W.S. 1809 gave the largest increases in yield but showed little increase in protein content. Neepawa gave intermediate responses in both yield and protein content. In general, the heaviest applications of fertilizer did not produce significant increases in yield beyond those produced by the lower applications.


1972 ◽  
Vol 12 (57) ◽  
pp. 414 ◽  
Author(s):  
CL Tuohey ◽  
AD Robson ◽  
DR Rooney

The effect of three times of initial cultivation (August, October, February-March) on grain yield, grain protein content, moisture conservation, and nitrate accumulation was studied over a period of seven years at three sites in the Wimmera on land that had been under medic ley. Fallowing in winter (August) or spring (October) markedly increased grain yields but not grain-protein content when compared with the non-fallow control (initial cultivation in February-March). Variation in yield response to both winter and spring fallowing appeared to be associated mainly with variation in moisture conservation in the 30-60 cm layer. With winter fallowing, the nitrate that accumulated was associated with yield increases, but with spring fallowing the nitrate appeared to he associated with yield depression. However, the role of nitrate accumulation in determining yield responses to fallowing was only of minor importance. Suppression of weeds in the crop was not a factor in producing the large yield responses to fallowing since crops on both fallowed and non-fallowed areas were generally weedfree. Results obtained in the current experiments indicate that the aspects of climate suggested by work in South Australia as being the ones that determine yield responses to fallowing are not the ones which are important in the Wimmera. In this environment the most promising predictors of yield responses to fallowing appear to be April to August rainfall before commencement of the winter fallow and September rainfall before commencement of the spring fallow.


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