Nitrogen nutrition of wheat following different crops

1992 ◽  
Vol 118 (2) ◽  
pp. 157-163 ◽  
Author(s):  
H. E. Echeverría ◽  
C. A. Navarro ◽  
F. H. Andrade

SUMMARYA trial using a split-plot with blocks design was carried out at the INTA Balcarce Experimental Station, Argentina on a typic argiudol soil to evaluate N nutrition in wheat after different preceding crops and using two rates of N fertilization (0 and 90 kg N/ha).Wheat (Triticum aestivum), soyabean (Glycine max), sunflower (Helianthus annuus) and maize (Zea mays) were grown in different combinations for two successive years (1984/85 and 1985/86).No water stress was detected during either growing season. Nitrogen availability was altered by the previous crops grown, but the effect lasted only for one season. Wheat following maize yielded least with no N and responded most to N fertilization. The highest yields of wheat without N and the lowest response by wheat to N fertilization were found after crops of soyabean and sunflower.Wheat after a fertilized wheat crop did not respond to N fertilization because of a serious attack of take-all (Gaeumannomyces graminis tritici).The nitrate concentration in wheat stem bases was found to be a good estimator of the availability of soil N.

2002 ◽  
Vol 42 (8) ◽  
pp. 1087 ◽  
Author(s):  
C. R. Kidd ◽  
G. M. Murray ◽  
J. E. Pratley ◽  
A. R. Leys

Winter cleaning is the removal of grasses from pasture using selective herbicides applied during winter. We compared the effectiveness of an early (June) and late (July) winter cleaning with an early spring herbicide fallow (September), spring (October) herbicide and no disturbance of the pasture on development of the root disease take-all in the subsequent wheat crop. Experiments were done at 5 sites in the eastern Riverina of New South Wales in 1990 and 1991. The winter clean treatments reduced soil inoculum of Gaeumannomyces graminis var. tritici (Ggt) compared with the other treatments at all sites as measured by a bioassay, with reductions from the undisturbed treatments of 52–79% over 5 sites. The winter clean treatments also significantly reduced the amount of take-all that developed in the subsequent wheat crop by between 52 and 83%. The early and late winter clean treatments increased the number of heads/m2 at 3 and 1 sites, respectively. Dry matter at anthesis was increased by the winter clean treatments at 3 sites. Grain yield was increased by the winter cleaning treatments over the other treatments at the 4 sites harvested, with yield increases of the early winter clean over the undisturbed treatment from 13 to 56%. The autumn bioassay of Ggt was positively correlated with spring take-all and negatively correlated with grain yield of the subsequent wheat crop at each site. However, there was a significant site and site × bioassay interaction so that the autumn bioassay could not be used to predict the amount of take-all that would develop.


1989 ◽  
Vol 29 (3) ◽  
pp. 455 ◽  
Author(s):  
GK McDonald

Very little nitrogen (N) fertiliser is applied to wheat crops in Australia. Currently, about 105 t of N fertiliser (less than 20% of Australia's total consumption) are used annually at an average rate of 2-3 kg Nha. This scant use of N fertiliser over much of the Australian wheat belt N is because the N derived from a legume-dominant pasture ley is thought to provide a wheat crop's N requirement. However, trends in the grain protein content of Australian wheat and some other indices of soil fertility suggest that legume-based pastures have not always been able to supply all the N required for adequate nutrition of the wheat crop and that there has been some occasional need for extra N from applications of fertiliser. Recent declines in the productivity and quality of pastures has further increased the need for supplementary applications of N fertiliser. The increase in grain legume production also has been partly based on the presumption that grain legumes contribute to the N economy of the following wheat crop. Many experiments throughout the wheat belt show a yield advantage of wheat grown after a grain legume, but these rotation trials also show that the level of productivity of the grain legume has little effect on the yield of the following wheat crop. A review of these experiments suggests that grain legumes, directly, contribute little to the N nutrition of a following wheat crop and their benefit may be from the legume acting as a disease break or providing the opportunity to control grassy weeds.


1987 ◽  
Vol 38 (6) ◽  
pp. 1011 ◽  
Author(s):  
GC MacNish ◽  
DA Nicholas

The relationship between grass production in subterranean clover pastures with two different rotation histories and take-all in a subsequent wheat crop following barley was studied. Grass production in the pastures ranged from 0 to 1700 kg ha-1. The incidence of take-all in the wheat crop ranged from 10 to l00%, while the take-all severity percentage ranged from 4 to 99.In one rotation series (pasture 9 years; barley, barley, pasture, wheat), each kilogram increase in grass production in the last pasture year caused a 0.087% increase in the take-all severity rating. In the second series (pasture 7 years; oats, pasture 3 years; barley, wheat), each kilogram increase in grass production caused a 0.040% increase in severity. These figures are significantly different (P < 0.05). Thus the field history ranging back at least four seasons influenced the effects that grass level in the last pasture year had on take-all severity. Reductions in wheat yields ranged from 8.6 to 10.5 kg ha-1 for each 1% increase in take-all severity rating.


2000 ◽  
Vol 51 (4) ◽  
pp. 445 ◽  
Author(s):  
J. A. Kirkegaard ◽  
M. Sarwar ◽  
P. T. W. Wong ◽  
A. Mead ◽  
G. Howe ◽  
...  

Biofumigation refers to the suppression of soil-borne pathogens and pests by biocidal compounds released by Brassica crops when glucosinolates (GSL) in their residues decay in soil. We conducted field studies at 2 sites to investigate the hypothesis that biofumigation by Brassica break crops would reduce inoculum of the take-all fungus Gaeumannomyces graminis var. tritici (Ggt) to lower levels than non-Brassica break crops, and thereby reduce Ggt infection and associated yield loss in subsequent wheat crops. High and uniform levels of Ggt were established at the sites in the first year of the experiments by sowing wheat with sterilised ryegrass seed infested with Ggt. Ggt inoculum declined more rapidly under Brassica crops than under linola and this reduction coincided with the period of root decay and reduced root glucosinolate concentrations around crop maturity. There was no consistent difference in inoculum reduction between canola (Brassica napus) and Indian mustard (Brassica juncea), nor between cultivars with high and low root GSL within each species. Despite significant inoculum reduction attributable to biofumigation, there were no differences in the expression of disease and associated impacts on the yield of subsequent wheat crops across the sites. Seasonal conditions, in particular the distribution of rainfall in both the summer–autumn fallow following the break crops and during the subsequent wheat crop, influenced inoculum survival and subsequent disease development. In wet summers, inoculum declined to low levels following all break crops and no extra benefit from biofumigation was evident. In dry summers the lower inoculum levels following brassicas persisted until the following wheat crops were sown but subsequent development of the disease was influenced more by seasonal conditions than by initial inoculum levels. Significant extra benefits of biofumigation were observed in one experiment where wheat was sown within the break crops to simulate grass weed hosts of Ggt. Under these circumstances there was greater reduction in Ggt inoculum under canola than linseed and an associated decrease in disease development. For host-dependent pathogens such as Ggt, we hypothesise that the benefits of biofumigation to subsequent wheat crops will therefore be restricted to specific circumstances in which inoculum is preserved during and after the break crops (i.e. dry conditions, grass hosts present) and where conditions in the following wheat crop lead to significant disease development (early sowing, wet autumn and spring, dry periods during grain filling).


2015 ◽  
Vol 154 (3) ◽  
pp. 472-486 ◽  
Author(s):  
S. L. BITHELL ◽  
A. C. McKAY ◽  
R. C. BUTLER ◽  
M. G. CROMEY

SUMMARYThe extent and severity of wheat take-all (caused by Gaeumannomyces graminis var. tritici (Ggt)) can vary considerably between growing seasons. The current study aimed to identify climatic factors associated with differing concentrations of Ggt DNA in soil and take-all disease at different stages of a sequence of wheat crops. Pre-sowing soil Ggt DNA concentrations and subsequent take-all disease in consecutive wheat crop sequences were compared across six seasons in 90 commercial cropping fields in Canterbury and Southland, New Zealand, between 2003 and 2009. Disease progress was assessed in additional fields in 2004/05 and 2005/06. While a general pattern in inoculum and disease fluctuations was evident, there were exceptions among wheat crop sequences that commenced in different years, especially for first wheat crops. In three consecutive growing seasons, there was very low inoculum increase in the first wheat crop, while increases in first wheat crops during the following three seasons was much greater. Low spring–summer rainfall was associated with low build-up of inoculum in first wheat crops. The inoculum derived from the first wheat then determined the amount of primary inoculum for the subsequent second wheat, thereby influencing the severity of take-all in that crop. Differing combinations of weather conditions during one wheat crop in a sequence and the conditions experienced by the next crop provided explanations of the severity of take-all at grain fill and the resulting post-harvest soil Ggt DNA concentrations in second wheat crops. Examples of contrasting combinations were: (a) a moderate take-all epidemic and high post-harvest inoculum that followed high rainfall during grain fill, despite low pre-sowing soil Ggt DNA concentrations; (b) severe take-all and moderate to high inoculum build-up following high pre-sowing soil Ggt DNA concentrations and non-limiting rainfall; and (c) low spring and early summer rainfall slowing epidemic development in second wheat crops, even where there were high pre-sowing soil Ggt DNA concentrations. The importance of the environmental conditions experienced during a particular growing season was also illustrated by differences between growing seasons in take-all progress in fields in the same take-all risk categories based on pre-sowing soil Ggt DNA concentrations.


2020 ◽  
Vol 12 (17) ◽  
pp. 2749
Author(s):  
Marta Aranguren ◽  
Ander Castellón ◽  
Ana Aizpurua

Nitrogen (N) splitting is critical to achieving high crop yields without having negative effects on the environment. Monitoring crop N status throughout the wheat growing season is key to finding the balance between crop N requirements and fertilizer needs. Three soft winter wheat fertilization trials under rainfed conditions in Mediterranean climate conditions were monitored with a RapidScan CS-45 (Holland Scientific, Lincoln, NE, USA) instrument to determine the normalized difference vegetation index (NDVI) values at the GS30, GS32, GS37, and GS65 growth stages. The threshold NDVI values in the Cezanne variety were 0.7–0.75 at the GS32, GS37, and GS65 growing stages. However, for the GS30 growing stage, a threshold value could not be established precisely. At this stage, N deficiency may not affect wheat yield, as long as the N status increases at GS32 stage and it is maintained thereafter. Following the NDVI dynamic throughout the growing season could help to predict the yields at harvest time. Therefore, the ΣNDVI from GS30 to GS65 explains about 80% of wheat yield variability. Therefore, a given yield could be achieved with different dynamics in wheat NDVI values throughout the growing cycle. The determined ranges of the NDVI values might be used for developing new fertilization strategies that are able to adjust N fertilization to wheat crop needs.


1979 ◽  
Vol 93 (2) ◽  
pp. 377-389 ◽  
Author(s):  
D. B. Slope ◽  
R. D. Prew ◽  
R. J. Gutteridge ◽  
Judith Etheridge

SUMMARYThe Rothamsted ley–arable experiments were on two fields with similar soils but with contrasting previous cropping: old grass on Highfield, old arable on Fosters field. Damage by take-all (Qaeumannomyces graminis var. tritici) occurred sooner in successive wheat crops grown after a lucerne ley and arable sequence (LU) than after a grass-clover ley and arable sequence (LC). On Highfield the difference was consistent and large, it occurred as soon as a second wheat crop was grown and resulted in wheat yielding 1 t/ha less after the LU than after the LC sequence. This difference did not persist in the next wheat crop where take-all was prevalent after both sequences. On Fosters field take-all developed more slowly and differences between sequences were mostly smaller.Wheat seedling bio-assay of soil cores from the LU and LC sequences showed that little take-all fungus persisted through the leys and that soils were much infested after a first wheat crop in the LU sequence on Highfield, but not in the LC sequence on Highfield or in either sequence on Fosters field. Microscopic examination of roots from assay seedlings and from field plants showed that Phialophora radicicola var. graminicola (PRG) was most common in soils where take-all developed slowly, but our results did not show if this was a causal relationship. The occurrence of much PRG in the LU sequence on Fosters conflicts with previous reports which associate large populations of this fungus only with grassland soils.


2013 ◽  
Vol 64 (6) ◽  
pp. 563 ◽  
Author(s):  
R. A. Lawes ◽  
V. V. S. R. Gupta ◽  
J. A. Kirkegaard ◽  
D. K. Roget

Break-crops such as legumes and oilseeds increase the yield of subsequent cereal crops by reducing the level of diseases and weeds that build in continuous cereal crops, and can also improve water and nitrogen supply. Although the term ‘break-crop’ originates from their role in breaking disease cycles of soil-borne diseases such as take-all (caused by Gaeumannomyces graminis var. tritici), the contribution of take-all control to the overall break-crop effect has not been separated in most studies. We re-analysed a range of medium- and short-term crop-sequencing experiments comprising 18 year × site combinations in diverse environments in southern Australia. An analysis using linear mixed effects models was conducted to: (i) define the agro-environments that lead to increases in take-all incidence in continuous wheat crop sequences, (ii) quantify the effect of take-all on wheat yield, and (iii) ascertain the contribution of the reduction in take-all following break-crops to the size of the total break-crop effect on wheat crop yield. Break-crop effects on wheat yield averaged 0.7 t/ha and ranged from 0 to 2.1 t/ha. On 14 of 18 occasions, take-all contributed to reduced wheat yield in continuous wheat rotations, although the estimated effect exceeded 0.1 t/ha on just six of those occasions. As a result, reduced take-all by break-crops contributed to <20% of the total break-crop effect in all but one instance, where the suppression accounted for 80% of the break-crop effect. In summary, although the break-crops improved wheat yield by 0.7 t/ha, the contribution from take-all control in the 14 locations where it could be quantified was just 0.1 t/ha. Correlation analysis revealed that take-all incidence in wheat was most likely to proliferate in colder, wetter environments. Take-all can severely damage crop yield, and the reduction contributes to the break-crop effect, but the average impact on wheat yield is small and poorly correlated with the potential yield of the wheat crop. The analytical approach helped to quantify the effect of take-all damage on crop yield, to provide further insight into the agro-environment that contributes to high levels of take-all incidence, and to demonstrate that take-all, like many other processes, operates in an episodic manner that is rare but, on occasions, severe.


1990 ◽  
Vol 115 (2) ◽  
pp. 209-219 ◽  
Author(s):  
J. McEwen ◽  
R. J. Darby ◽  
M. V. Hewitt ◽  
D. P. Yeoman

SUMMARYThe effects on a winter wheat test crop of a preliminary year of winter or spring field beans (Vicia faba), winter oats, winter oilseed rape, winter or spring peas (Pisum sativum), winter wheat, spring lupins (Lupinus albus), spring sunflowers (Helianthus annuus) or a cultivated fallow were compared in three 2-year experiments on clay-with-flints soil at Rothamsted from 1986 to 1989. In one experiment, autumn-sown ryegrass (Lolium perenne) and an uncultivated fallow, given weedkiller, were also included in the first year. Plots of test-crop wheat were divided to compare no N fertilizer with an optimal amount estimated from a predictive model.Amounts of take-all (Gaeumannomyces graminis) in the test crop of wheat following wheat were very slight in the first experiment, but large in the second and third. All the break crops reduced takeall to none or very slight amounts.Amounts of NO3-N in the soil in autumn after the first-year crops ranged from 7 to 95 kg N/ha. On average, they were least after oats, and most after cultivated fallow. In autumn 1988they were least after autumn-sown ryegrass. In early spring, amounts of NO3-N were generally less, ranging from 7 to 55 kg N/ha, depending on preceding crops, sowing date of the wheat and the weather. Amounts of NH4-N in soil were little affected by preceding crops or weather and were generally smaller in spring.The estimated average N fertilizer requirement of test-crop wheat following winter wheat was 230kg N/ha. This was increased by 10 kg N/ha following winter oats, decreased by 40 kg N/ha after spring peas and by 30 kg N/ha after winter rape, winter peas, spring beans and cultivated fallow. Other preliminary crops not represented every year had effects within this range.Grain yields of test-crop wheat given optimal N averaged 7·2 t/ha after winter wheat, c.1·5 t/ha less than the average after most of the break crops. The yield after oats was limited by self-sown ‘volunteers’ and that after ryegrass by limited soil N after ploughing.Of the break crops tested, winter and spring beans, winter oats, winter rape and spring peas all gave satisfactory yields. A farmer should choose between these on the basis of local farm circumstances and current economics of the break crops. Differences between effects on take-all and savings on fertilizer N were too small to influence this decision.


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