Soil and tissue tests to predict the potassium requirements of canola in south-western Australia

2006 ◽  
Vol 46 (5) ◽  
pp. 675 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

The predominantly sandy soils of south-western Australia have become potassium (K) deficient for spring wheat (Triticum aestivum L.) production due to the removal of K from soil in grain and hay. The K requirements of canola (rape, Brassica napus L.) grown in rotation with wheat on these soils are not known and were determined in the study reported here. Seed (grain) yield increases (responses) of canola to applications of fertiliser K occurred at sites where Colwell soil test K values (top 10 cm of soil) were <60 mg/kg soil. Grain yield responses to applied K occurred when concentrations of K in dried shoots were <45 g/kg for young plants 7 and 10 weeks after sowing and <35 g/kg for 18 weeks after sowing. Application of fertiliser K had no significant effects on either oil or K concentrations in grain.

2007 ◽  
Vol 47 (8) ◽  
pp. 976 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

Most soils used for agriculture in south-western Australia are sandy and are now deficient in both potassium (K) and nitrogen (N) for cereal and canola (oilseed rape; Brassica napus L.) grain production. However, the effect of applying different levels of both fertiliser K and N on grain yields of these crops is not known. We report results of 10 field experiments, conducted on sandy soils in the region, to measure the effects of applying both K and N on canola grain yields and concentration of oil and protein in grain. Four levels of K (0–60 kg K/ha as potassium chloride) and four levels of N (0–138 kg N/ha as urea) were applied. Significant grain yield responses to applied N occurred in all experiments for the nil-K treatment and each level of K applied, with responses increasing as more N was applied. For all levels of N applied, significant grain yield responses occurred when up to 30 kg K/ha was applied, with no further significant grain yield responses occurring when 60 kg K/ha was applied. The K × N interaction was always significant for grain production. Application of K had no effect on the concentration of oil and protein in grain. Application of N consistently decreased concentration of oil and increased concentration of protein in grain. The K × N interaction was not significant for concentration of oil or protein in grain, but application of up to 30 kg K/ha significantly increased canola grain and so oil yields (concentration of oil in grain multiplied by grain yield). Our results are likely to be relevant for all acidic to neutral sandy soils worldwide used for growing canola crops.


2006 ◽  
Vol 46 (8) ◽  
pp. 1061 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

The sulfur (S) requirements of canola (Brassica napus L.) grown in rotation with spring wheat (Triticum aestivum L.) and lupin (Lupinus angustifolius L.) in south-western Australia are not known. This study, involving 59 experiments, was conducted from 1993 to 2003 to determine soil and tissue test values for canola grain production below which S deficiency is likely. Extraction of S from soil using 0.25 mol KCl/L at 40°C (KCl-40 procedure) for the top 10 cm of soil is the standard soil test for S in the region. We measured KCl-40 values for soil samples collected at soil depths of 0–10, 10–20 and 20–30 cm and related the values to canola grain yield responses to applied fertiliser S measured at the end of the growing season. Total S measured in dried shoots at about 90 days after sowing (DAS) was related to shoot yields at 90 DAS and grain yields. In addition, the concentration of oil in canola grain was measured to see if applications of S affected oil concentrations. Soil test S was higher in the subsoil than in the top 10 cm of soil at about half the sites comprising sandy duplex soils with larger capacities to sorb sulfate in the subsoil. Significant grain yield responses to applied S occurred for soil test values <7 mg/kg to 30 cm. At many sites when soil test S was <7 mg/kg in the top 10 cm of soil, shoots showed grain yield responses to applied S, but canola roots eventually accessed sufficient S in the subsoil for grain production, so that no grain yield responses to applied fertiliser S occurred. Therefore, tissue test values for dried shoots at 90 DAS poorly predicted S deficiency for grain production. Responses of shoots and grain to applied S occurred for S concentrations in shoots <4 g/kg. We conclude that shallow soil tests and early tissue testing may both overestimate the magnitude of an S deficiency for grain production of canola grown in sandy WA soils. Deeper soil tests need to be seriously considered. Applications of fertiliser S mostly had no consistent effect on concentrations of oil in canola grain.


2020 ◽  
Vol 71 (12) ◽  
pp. 959
Author(s):  
Malcolm R. McCaskill ◽  
Penny Riffkin ◽  
Amanda Pearce ◽  
Brendan Christy ◽  
Rob Norton ◽  
...  

Nutrient deficiencies are considered a reason for commercial yields of wheat (Triticum aestivum L.) and canola (Brassica napus L.) in the high-rainfall zone (HRZ) of southern Australia being well below predicted potential yields. With the aim of developing soil-test interpretation guidelines suitable for HRZ conditions, nutrient-response experiments, 15 with wheat and 12 with canola, were conducted between 2015 and 2018. These experiments quantified responses to nitrogen (N), phosphorus (P), potassium (K), sulfur (S), copper (Cu) and zinc (Zn) in pre-sowing soil tests. The highest yielding treatment of the wheat experiments averaged 7.1 t/ha (range 2.6–10.8 t/ha), and of the canola experiments 4.2 t/ha (range 0.7–6.2 t/ha). The most frequent responses were to N and P, followed by S and K. There were no significant positive responses to Cu or Zn. Across the experiments, the 95% critical value for Colwell P in wheat was 52 mg/kg, with a 95% confidence range of 39–68 mg/kg. For canola, the critical value was 59 mg/kg, with a range of 38–139 mg/kg. These values are higher than from lower rainfall regions of Australia. Critical values for K and S were also higher than from drier regions of Australia. The Sprengel–Lieberg Law of the Minimum overestimated yield where there were multiple nutrient limitations, whereas an equivalent Law of the Product underestimated yield under these conditions. These higher critical values based on evidence from the HRZ are expected to assist in closing the yield gap for wheat and canola in the region.


1990 ◽  
Vol 70 (4) ◽  
pp. 629-639 ◽  
Author(s):  
W. F. NUTTALL ◽  
R. G. BUTTON

This study was conducted to determine if deep banding of P fertilizer was as efficient as placing P in a band with the seed. Phosphorus fertilizer (MAP) was deep banded at rates of 0, 10, 20, and 30 kg of P ha−1 which was compared with equal rates applied with the seed, and with one-half seed placed, one-half deep banded. The P rates were applied onto the same plots each year in a cropping sequence of canola (Brassica napus L.), four crops of wheat (Triticum aestivum L.) and then canola. Plots were located on a Melfort silty clay soil (Orthic Black Chernozem). In combination with MAP treatments, ammonium nitrate was applied by deep banding and by broadcast-incorporation to bring the total N application rate to 75 kg ha−1. Control treatments of 0–0 and 11–20 kg of N-P, respectively, were also included. In the first year of the experiment, when soil moisture conditions were dry, seed placement of the P fertilizer, on average, resulted in a significantly higher grain yield (1.01 t ha−1) of canola than deep banding (0.88 t ha−1). In the last year of the experiment, canola grain yields for the two placements were not significantly different (1.87 vs. 1.83 t ha−1). Over the 4 yr that wheat was grown there was no significant difference in grain yield between seed placed P and deep banding (2.97 vs. 2.95 t ha−1). Seed placement of P resulted in a higher grain yield (3.05 t ha−1) with N broadcast than with N deep banded (2.90 t ha−1), but with half-seed plus half-deep-banded P the yield was higher with N deep banded (3.08 t ha−1) than with broadcast-incorporated (2.87 t ha−1). The application of N and P over the 6 yr increased the available P in the soil from 7.5 (control) to 12.9 μg of P g−1 soil (N P treatments with 75 kg N ha−1). In general the application of P fertilizer either by deep banding or placement with the seed of the crop gave similar yields with the exception that at the low rates of P, seed placement was better for canola in the first year of the crop sequence. Key words: Deep banding, N, P, canola, wheat, placement


2007 ◽  
Vol 47 (8) ◽  
pp. 984 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

The effect of fertiliser phosphorus (P) and nitrogen (N) on seed (grain) yield and concentration of oil and protein in grain of canola (oil-seed rape; Brassica napus L.) was measured in two field experiments undertaken at eight sites from 1993–2005 in south-western Australia, on soils deficient in P and N. Six rates of P (0–40 kg P/ha as single superphosphate) and four rates of N (0–138 kg N/ha as urea) were applied. Significant grain yield increases (responses) to applied P occurred in both experiments and these responses increased as rates of applied N increased. For grain production, the P × N interaction was significant in all eight years and locations of the two experiments. Application of P had no effect on concentration of oil and protein in grain. Application of N always decreased the concentration of oil and increased the concentration of protein in grain. For canola grain production in the region, responses to applied N always occur whereas responses to applied P are rare, but if soil P testing indicates likely P deficiency, both P and N fertiliser need to be applied.


2006 ◽  
Vol 46 (5) ◽  
pp. 645 ◽  
Author(s):  
M. D. A. Bolland ◽  
R. F. Brennan ◽  
P. F White

The phosphorus (P) requirements of spring wheat (Triticum aestivum L.) are well known for all soils in south-western Australia; but the P requirements of field pea (Pisum sativum L.) and canola (Brassica napus L.), which are grown in rotation with wheat on marginally acidic to alkaline soils in the region, are not known. In a glasshouse study, the P requirements of field pea and wheat were compared for 16 soils collected throughout the agricultural region. Ten of the 16 soils were also used to compare the P requirements of canola and wheat. The P was applied as powdered single superphosphate, and yield of dried shoots of 42-day-old plants was measured. The amount of P required to produce 90% of the maximum yield of dried shoots (PR90 values) was used to compare the P requirements of the species. To produce 90% of the maximum yield, field pea required less P than wheat in 5 soils, similar P in 2 soils, and more P in 9 soils. Canola required less P than wheat in all 10 soils. We conclude the P requirements of field pea or canola relative to wheat depend on a complex interaction between plant and soil, particularly for field pea relative to wheat. Per unit of applied P, the P concentration in dried shoots decreased in the order canola > wheat > field pea, indicating the order in which plant roots of the 3 species were able to access P from soil.


1978 ◽  
Vol 58 (1) ◽  
pp. 241-248 ◽  
Author(s):  
J. WADDINGTON

Under greenhouse conditions, incorporating ground straw in the soil at rates between 2,240 and 8,970 kg/ha reduced the emergence of alfalfa (Medicago media Pers. cv. Beaver) significantly (P < 0.05) and bromegrass (Bromus inermis Leyss cv. Magna) slightly, but had no effect on barley (Hordeum vulgare L. cv. Conquest). Rape (Brassica napus L. cv. Target and B. campestris L. cv. Echo) straws were more damaging than wheat (Triticum aestivum L. cv. Manitou) straw. Symptoms of severe nitrogen deficiency appeared early in the growth of barley where straw had been added to the soil. The effect on tillering varied. In one experiment tillers were smaller, in one tillers were larger; but in both, total leaf area produced was much less where 8,970 kg/ha of straw had been added to the soil. Bromegrass showed the same effects but to a lesser degree, probably because of slower growth requiring a smaller supply of nitrogen. Alfalfa growth was apparently unaffected. There was no evidence that the straw of either rapeseed species was more deleterious than wheat straw to crop growth after emergence. It is concluded that straw incorporated in soil affected barley and bromegrass growth by reducing the availability of nitrogen.


2013 ◽  
Vol 182 ◽  
pp. 335-342 ◽  
Author(s):  
Stefan. B. Bengtsson ◽  
Jan Eriksson ◽  
Annemieke I. Gärdenäs ◽  
Mykhailo Vinichuk ◽  
Klas Rosén

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