Comparing the potassium requirements of canola and wheat

2007 ◽  
Vol 58 (4) ◽  
pp. 359 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

Most sandy soils used for cropping in south-western Australia are now deficient in potassium (K) due to removal of K from soil in hay and grain, and profitable grain yield responses to applied fertiliser K are commonly obtained for spring wheat (Triticum aestivum L.) and canola (oilseed rape, Brassica napus L.). However, there are only limited data comparing the K requirements of these 2 species in the region. In a glasshouse experiment we compared the K requirements of wheat (cv. Westonia), conventional canola cv. Outback (cultivars of canola not produced by classical breeding techniques to be tolerant of specific herbicides), triazine-tolerant (TT) canola cvv. Pinnacle and Surpass 501, and imidazolinone-tolerant (IT) canola cv. Surpass 603. The following measures were used: yield of 54-day-old dried shoots and seed (grain) without added K, applied K required to produce 90% of the maximum yield of shoots and grain, K required to attain a K concentration in shoots of 30 g/kg, and K required to achieve a K content in shoots (K concentration multiplied by yield) of 40 mg/pot. We also determined for each species and cultivar the concentration of K in dried shoots that was related to 90% of the maximum grain yield, to estimate critical concentration in shoots below which K deficiency was likely to reduce grain production. All 4 canola cultivars produced similar results. Both canola and wheat produced negligible shoot yields and no grain when no K was applied. For each species and cultivar the amount of applied K required to produce 90% of the maximum yield was similar for shoots and grain, and was ~121 mg K/pot for the 4 canola cultivars and 102 mg K/pot for wheat, so ~19% more K was required for canola than for wheat. For each amount of K applied, the concentration of K in shoots was greater for canola than for wheat. The amount of applied K required to attain a K concentration of 30 g K/kg in shoots was ~96 mg K/pot for canola and 142 mg K/pot for wheat, so ~48% more K was required by wheat than by canola. The amount of K applied required to achieve a K content of 40 mg K/pot in shoots was ~46 mg K/pot for canola and 53 mg K/pot for wheat, so ~13% more applied K was required by wheat than by canola. The data suggest that canola roots were better able to obtain K from soil than wheat roots, but wheat used the K taken up more effectively than canola to produce shoots and grain. The concentration of K in dried shoots of 54-day-old plants that was related to 90% of the maximum dried shoot yield or grain was ~32 g/kg for canola and ~23 g/kg for wheat.

2004 ◽  
Vol 44 (3) ◽  
pp. 309 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

We compared the potassium (K) response of canola (Brassica napus L. cv. Karoo), spring wheat (Triticum aestivum L. cv. Camm), narrow-leaf lupin (8 cultivars of Lupinus angustifolius L.), and yellow lupin (2 cultivars of L. luteus L.) in a glasshouse experiment. The following measures were used: yield without added K; K required for 75% of the maximum yield; K required to achieve a K concentration in shoots of 20 g/kg; K required to achieve a K content of 50 mg K/pot in dried shoots (K concentration multiplied by yield); and, for the L. angustifolius cultivars, the K efficiency ratio (yield for the nil-K treatment divided by yield for the largest amount of K applied).Both L. angustifolius and L. luteus used soil K and applied K more effectively than canola and wheat to produce shoots (measured from dried shoots of 42-day old seedlings). For all amounts of K applied, including the nil treatment, the K concentrations were higher in canola and wheat shoots than in shoots of the 2 lupin species. Consequently, the 2 lupin species were less effective than canola and wheat at taking up soil and applied K, but were more effective at using the K taken up to produce shoots. The most recent cultivar of L. angustifolius, cv. Kalya, was less effective than the older Merrit cultivar at using soil and applied K to produce shoots, therefore future cultivars need to be screened for their ability to use soil and applied K. The K efficiency ratio for L. angustifolius indicated cultivars Kalya and 2141 were inefficient and the following cultivars had similar medium efficiency values: Myallie, Tanjil, Tallerack, Quilinock, Belara and Merrit. As measured in 42 day old seedlings, the diagnostic critical concentration of K in shoots required for 90% maximum yield of dried shoots was about (g K/kg) 40 for wheat, 37�for canola, 16 for L. angustifolius and 14 for L. luteus.


2016 ◽  
Vol 67 (11) ◽  
pp. 1168 ◽  
Author(s):  
Qifu Ma ◽  
Richard Bell

Although soil salinity and potassium (K) deficiency are widespread in agricultural lands, there is a paucity of knowledge about the interactive effects of sodium (Na) and K on the growth and yield of major grain crops. In pot experiments, we examined salt tolerance of canola (Brassica napus L.), narrow-leafed lupin (Lupinus angustifolius L.) and wheat (Triticum aestivum L.), and crop K requirement under Na supply ranging from low to high. Plant growth and seed yield of all three crops were lower at 40 mg K/kg than at 100 mg K/kg soil. Although 100 mg Na/kg (4 dS/m in soil solution) had little effect on canola cv. Boomer and wheat cv. Wyalkatchem, the salt-treated narrow-leafed lupin cv. Mandelup died at 47 days after sowing, regardless of amount of soil K. In low-K soils, canola with 100 mg Na/kg and wheat with 50 mg Na/kg did not show K-deficiency symptoms and produced greater seed yield than plants with nil Na addition. At 100 mg K/kg, Na-induced reduction in growth and yield occurred only to plants with 200 mg Na/kg. However, at 160 mg K/kg, 200 mg Na/kg did not have an adverse effect. In canola and wheat, shoot K concentration increased and shoot Na concentration decreased with increasing amount of soil K; however, high soil K did not reduce shoot Na concentration in narrow-leafed lupin. The study showed that narrow-leafed lupin was very susceptible to salinity, whereas canola and wheat plants were relatively salt-tolerant. The stimulation of growth and yield in canola and wheat by low–moderate Na in low-K soils suggests partial K substitution by Na, and that adaptation of canola and wheat to salt-affected soils can be enhanced by high K supply.


Soil Research ◽  
2000 ◽  
Vol 38 (3) ◽  
pp. 745 ◽  
Author(s):  
M. T. F. Wong ◽  
N. K. Edwards ◽  
N. J. Barrow

The B horizon of duplex soils in the wheatbelt of Western Australia is sometimes enriched with potassium (K). K supply from this source is, however, not taken into account in fertiliser recommendations based on soil tests on samples from the 0–10 cm layer. Grain yield responses of wheat to K were measured over 4 years on 10 duplex soils in the medium rainfall (400–600 mm) regions of the West Australian wheatbelt. The depth at which the texture changed markedly ranged from 25 to 75 cm. K was measured through the profile and the concentration was reduced to a single value with a weighting equation that takes account of the distribution of root length. The weights chosen by the fitting procedure discounted the K content of the subsoil severely and provided no evidence that subsoil K was important in determining yield. Furthermore, the improvement obtained by using the weighted K concentration in the 0–1 m layer compared with using the topsoil (0–10 cm) analysis was not statistically significant. K deficiency can be diagnosed in those soils using analysis of the 0–10 cm samples only.


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.


2006 ◽  
Vol 46 (5) ◽  
pp. 659 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

Potassium (K) deficiency is now common in sandy soils of south-western Australia and the K requirements of most pasture species grown in rotation with crops in the region are not known. In a glasshouse experiment using a K deficient yellow sand, we compared the K requirements of 5 pasture species now commonly grown in the region: French serradella (Ornithopus sativus Brot.) cv. Cadiz, yellow serradella (Ornithopus compressus Brot.) cv. Santorini, balansa clover [Trifolium balansae, classified as T. michelianum Savi var. balansae (Boiss)] cv. Paradana, 2 subterranean clover (Trifolium subterraneum L.) cultivars, cv. Seaton Park (subspecies subterraneum) and cv. Trikkala (subspecies yanninicum), and annual ryegrass (Lolium rigidum Gaud) cv. Wimmera. After 56 days of growth, above-ground growth was harvested and analysed for total K. Mitscherlich curves were fitted to yield of dried shoots, K concentration and K content (K concentration multiplied by yield) of the shoots. These fitted curves were used to determine the amount of K required to produce 75% of the maximum yield of dried shoots, K required to attain a K concentration in dried shoots of 25 g/kg, and K required to achieve a K content in dried shoots of 250 mg K/pot. Annual ryegrass and yellow serradella more effectively used indigenous soil K and applied K to produce dried shoots than the other species and cultivars, with the other species and cultivars requiring about 55% more applied K to produce 75% of the maximum shoot yield. The K content in dried shoots estimated the total K taken up from the soil, and annual ryegrass took up least K from soil, but it required least applied K to produce 75% of the maximum shoot yield, indicating it used the K it took up very effectively to produce shoots. Yellow serradella took up most K and, after annual ryegrass, it needed least applied K to produce the target yield of dried shoots. After yellow serradella, subterranean clover cv. Trikkala took up most K from soil, but it required nearly the most applied K to produce the target shoot yield so it was inefficient at using K taken up to produce the shoots. For all the other species and cultivars, K requirement was similar as assessed by yield or K content data. The critical concentration of K required for 90% maximum yield of dried shoots was about (g K/kg) 24 for balansa clover, 23 for both subterranean clover cultivars, 21 for yellow and French serradella, and 15 for annual ryegrass.


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.


2009 ◽  
Vol 60 (6) ◽  
pp. 566 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

Canola (oilseed rape, Brassica napus L.) is now grown in rotation with spring wheat (Triticum aestivum L.) on the predominantly sandy soils of south-western Australia. For both crop species, fertiliser nitrogen (N) and phosphorus (P) need to be applied for profitable grain production. The fertiliser N requirements have been determined separately for canola or wheat when adequate P was applied. By contrast, the fertiliser P requirements of the 2 species have been compared in the same experiment when adequate N was applied and showed that canola consistently required ~25–60% less P than wheat to produce 90% of the maximum grain yield. We report results of a field experiment conducted at 7 sites from 2000 to 2003 in the region to compare grain yield responses of canola and wheat to application of N and P in the same experiment. Four levels of N (0–138 kg N/ha as urea [46% N]) and 6 levels of P (0–40 kg P/ha as superphosphate [9.1%P]) were applied. Significant grain yield responses to applied N and P occurred for both crop species at all sites of the experiment, and the N × P interaction for grain production was always significant. To produce 90% of the maximum grain yield, canola required ~40% more N (range 16–75%) than wheat, and ~25% less P (range 12–43%) than wheat. For both crop species at 7 sites, applying increasing levels of N had no significant effect on the level of P required for 90% of maximum grain yield, although at 1 site the level of P required to achieve the target yield for both crop species when no N was applied (nil-N treatment) was significantly lower than for the other 3 treatments treated with N. For both crop species at all 7 sites, applying increasing levels of P increased the level of N required for 90% of the maximum grain yield. Fertiliser P had no significant effect on protein concentration in canola and wheat grain, and oil concentration in canola grain. As found in previous studies, application of increasing levels of N decreased oil concentration while increasing protein concentration in canola grain, and increased protein concentration in wheat grain. The N × P interaction was not significant for protein or oil concentration in grain. Protein concentrations in canola grain were about double those found in wheat grain.


2008 ◽  
Vol 59 (11) ◽  
pp. 983 ◽  
Author(s):  
M. D. A. Bolland ◽  
R. F. Brennan

Spring wheat (Triticum aestivum L.), lupin (Lupinus angustifolius L.), and canola (Brassica napus L.) are the major crop species grown in rotation on the predominantly sandy soils of south-western Australia. Comparisons among the species for yield responses to applied phosphorus (P), effects of applied P on growth rates of shoots, P response efficiency for shoot and grain production, and the pattern for accumulation of P into shoots during growth and into grain at maturity are rare, or are not known, and were quantified in the glasshouse study reported here. Size and P content (P concentration multiplied by yield) of sown seed were in the order canola < wheat < lupin. Therefore, yield responses to applied P were first observed at ~10 days after sowing (DAS) for canola, ~17 DAS for wheat, and ~60 DAS for lupin. Lupin shoots showed no yield response to applied P at the first harvest at 51 DAS. Otherwise all species showed large yield, P concentration, and P content responses to applied P for all harvests at 51, 78, 87, 101, 121, and 172 DAS. To produce 90% of the maximum grain yield, the relevant data for cropping, lupin required ~67% less P than wheat, canola required ~40% less P than wheat, and canola required ~75% more P than lupin. Growth rates, and P response efficiency, were generally largest for canola, followed by wheat, then lupin. For shoots, P accumulation was in the order lupin > wheat > canola at 51 DAS, canola > wheat > lupin at 78 and 87 DAS, canola > wheat = lupin at 101 DAS, and all 3 species were about similar at 121 DAS. For accumulation of P into shoots plus grain at maturity (172 DAS) the order was canola > lupin > wheat, and for grain only was canola > wheat = lupin.


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.


2004 ◽  
Vol 44 (10) ◽  
pp. 1025 ◽  
Author(s):  
R. F. Brennan ◽  
M. D. A. Bolland

An old phosphate rock experiment was used to determine critical Colwell soil test phosphorus values for spring wheat (Triticum aestivum L.) and canola (rape, Brassica napus L.). Different amounts of phosphorus, applied to the soil 16 years previously as triple superphosphate and phosphate rock fertilisers, and different amounts of triple superphosphate applied in the current year, were used to generate soil with different P status. The phosphorus fertilisers contained different concentrations of cadmium as an impurity. The experiment was thus used to relate soil test cadmium, measured using 0.005 mol CaNO3/L, to cadmium concentration in grain. Colwell soil test phosphorus, related to 90% of the maximum grain yield (critical value), was 58 mg phosphorus/kg soil for wheat and 19 mg phosphorus/kg soil for canola. In soil with low Colwell phosphorus concentrations, canola efficiently used phosphorus that was banded with the seed while sowing (drilled phosphorus), requiring 15 kg phosphorus/ha as triple superphosphate to achieve 90% of the maximum yield, compared to 65–70 kg phosphorus/ha for wheat. Soil test cadmium was highly correlated with grain cadmium in both wheat (R2 = 0.89) and canola (R2 = 0.96), suggesting soil testing for cadmium may be used to predict the likelihood of grain cadmium contamination.


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