Prediction of yield responses to phosphorus by established Greenleaf desmodium/grass pastures in south-east Queensland using chemical tests

1980 ◽  
Vol 20 (105) ◽  
pp. 477
Author(s):  
GE Rayment ◽  
RC Bruce ◽  
BG Cook
Keyword(s):  
Soil Phosphorus ◽  
Residual Variance ◽  
Total Soil ◽  
Plant Chemical ◽  
Diagnostic Samples ◽  
Total Soil Phosphorus ◽  
Independent Variable ◽  
Phosphorus Status ◽  
Yield Responses ◽  
Phosphorus Levels

Phosphorus topdressing experiments (rates to 60 kg P ha-1) on 18 commercial Desmodium intortum cv. Greenleaf/grass pastures were conducted over a 4-year period in south-east Queensland. The aim was to determine whether yield responses, which occurred only in the Greenleaf component at six sites, could be predicted using soil or plant chemical tests. Acid-(0.005 M H2SO4) and bicarbonate-(0.5 M NaHCO3) extractable tests of phosphorus status in 0-10 cm soil samples each explained about 60% of the variance in Greenleaf relative yields. The residual variance was not significantly reduced by the inclusion of terms for total soil nitrogen, total soil phosphorus, exchangeable calcium and pH into the independent variable. These empirical soil phosphorus tests had higher predictive value than plant tests based on phosphorus concentrations in tops and diagnostic samples of Greenleaf. With both acid- and bicarbonate-extractable phosphorus, yield responses are likely in the Greenleaf component when phosphorus levels in most soils are below 22 ppm. Above 29 ppm, no response would be expected

Effect of topdressed phosphorus fertilizer on established white clover based pastures in south-east Queensland. 1. Prediction of yield responses using soil tests

1979 ◽  
Vol 19 (99) ◽  
pp. 454 ◽  
Author(s):  
GE Rayment ◽  
RC Bruce
Keyword(s):  
White Clover ◽  
Field Experiments ◽  
Soil Phosphorus ◽  
Relative Yield ◽  
Pasture Production ◽  
Phosphorus Status ◽  
Empirical Tests ◽  
Yield Responses ◽  
Phosphorus Levels ◽  
Term Field

Seventeen short-term field experiments were conducted over a five year period in south-east Queensland in which rates of up to 60 kg P ha-1 as monocalcium phosphate were topdressed onto established, previously grazed, grass-white clover (Trifolium repens) pastures, Increases (P < 0.05) in yields of white clover were obtained at seven sites, but concurrent increases in grass production occurred at only four sites. Higher total pasture production resulted at six of these sites. One quantitative (total) and two empirical (0.005 M H2SO4 and 0.5 M Na HCO3) estimates of phosphorus status in 0-10 cm soil samples, collected prior to topdressing treatments, were separately correlated with relative yield responses of white clover, grass and total pasture components. Although soil phosphorus levels by all methods were statistically intercorrelated (P < 0.01), acid-extractable and total phosphorus tests were generally unsuitable for predictive purposes, having low coefficients of determination for regressions and Cate-Nelson separations of responsive from non-responsive sites. Bicarbonate-extractable phosphorus proved the most suitable soil test. It accounted for 60 and 44% of the variance in relative yields of white clover and total pasture, respectively, but was poorly correlated with relative yields of grass. The suggested critical level of soil phosphorus (bicarbonate extraction) for white clover is 28 ppm P. For total pasture, responses are likely below 22, unlikely above 28 and uncertain between 22 and 28 ppm P, respectively. Percentage variance in relative yields already explained by both empirical tests was not significantly increased by inclusion of terms for pH and exchangeable calcium into the X variable.

Using soil and plant analyses in decisions about fertilisers: a farmer’s perspective

1998 ◽  
Vol 38 (7) ◽  
pp. 745 ◽  
Author(s):  
W. R. Gibson
Keyword(s):  
Soil Phosphorus ◽  
Phosphorus Concentration ◽  
Plant Analysis ◽  
Ph Measurements ◽  
Initial Soil ◽  
Potassium Application ◽  
Phosphorus And Potassium ◽  
Yield Responses ◽  
The Relationship ◽  
Phosphorus Levels

Summary. This paper describes the part played by soil and plant analysis in decisions about fertilisers used on a mixed pastoral and cropping farm at Scone, in the Northern Midlands of Tasmania. Measurements of phosphorus and potassium concentrations in soils provide an essential framework for choosing fertilisers for crops and pastures. Use of lime with certain crops is determined by pH measurements. Neither soil nor plant analysis are used in choosing nitrogenous fertilisers. Fifteen paddocks were tested 7–8 years after initial soil tests (Colwell extracts). Phosphorus concentrations (mean ± s.e.) had risen by 13 ± 5 µg/g (P<0.05) and potassium by 89 ± 19 µg/g (P<0.001). In addition, the relationship between changes in these concentrations and the total phosphorus or potassium applied to individual paddocks was examined. Phosphorus concentration rose (P<0.001) by 5.9 µg/g for each 10 kg/ha additional phosphorus applied over the 7–8 years. Application of phosphorus at 7 kg/ha annually was enough to maintain soil phosphorus levels. No such relationship was detected for potassium. Application of lime at 4 t/ha raised the pH by about 1 unit. These results provide some reassurance about the behaviour of soils on Scone in response to the practices used in commercial mixed farming. The importance for the farmer of analyses being reliable is stressed, as is the need for well-based interpretation of the analytical results in order that the yield responses to fertilisers can be foreseen. Evidence about the financial returns produced by the increased yields is often lacking, especially for grazing enterprises.

scholarly journals Impact of Plant Invasion and Increasing Floods on Total Soil Phosphorus and its Fractions in the Minjiang River Estuarine Wetlands, China

Wetlands ◽  
2015 ◽  
Vol 36 (1) ◽  
pp. 21-36 ◽  
Author(s):  
Wei-Qi Wang ◽  
Jordi Sardans ◽  
Cong-Sheng Zeng ◽  
Chuan Tong ◽  
Chun Wang ◽  
...  
Keyword(s):  
Plant Invasion ◽  
Soil Phosphorus ◽  
Estuarine Wetlands ◽  
Minjiang River ◽  
Total Soil ◽  
Total Soil Phosphorus ◽  
River Estuarine

Accumulation of plant nutrients and changes in soil properties of sandy soils under fertilized pasture in southeastern South-Australia .I. Phosphorus

Soil Research ◽  
1987 ◽  
Vol 25 (2) ◽  
pp. 193 ◽  
Author(s):  
DC Lewis ◽  
AL Clarke ◽  
WB Hall
Keyword(s):  
Organic Phosphorus ◽  
Soil Phosphorus ◽  
Balance Sheet ◽  
South Australia ◽  
Single Superphosphate ◽  
Phosphorus Accumulation ◽  
Total Soil Phosphorus ◽  
Clay Layers ◽  
Stocking Rates ◽  
Phosphorus Levels

The accumulation of phosphorus applied as superphosphate over a 25-year period to pastures growing on sand over clay soils was measured in three areas of different rainfall in the south-east of South Australia. Total soil phosphorus levels increased in the 0-10 cm, 10-30 cm and 30 cm-clay layers for all areas, but no accumulation occurred in the clay layer. For every 100 kg ha-1 of single superphosphate (9.6% phosphorus) applied, 2.0, 3.2 and 3.5 kg ha-1 of phosphorus accumulated in the 0-10 cm layer for the Hundreds of Coles, Willalooka and Senior respectively. The recoveries of applied phosphorus in the sand layer for the three areas were 42, 57 and 75% for Coles, Willalooka and Senior respectively. The annual accumulation rates of organic phosphorus in the top 30 cm of soil ranged from 2.4 to 3.5 kg ha-1. By using a 'balance sheet' approach, the annual maintenance phosphate requirements for the three areas were calculated. These ranged from 60 to 165 kg ha-1 of superphosphate, and were associated with differences in leaching losses, stocking rates and organic phosphorus accumulation.

Effect of topdressed phosphorus fertilizer on established white clover based pastures in south-east Queensland. 2. Macronutrient status and prediction of yield responses using plant chemical tests

1979 ◽  
Vol 19 (99) ◽  
pp. 463 ◽  
Author(s):  
GE Rayment ◽  
RC Bruce
Keyword(s):  
White Clover ◽  
Field Experiments ◽  
Early Summer ◽  
Nutrient Concentrations ◽  
Phosphorus Concentration ◽  
Pasture Production ◽  
Plant Chemical ◽  
Diagnostic Samples ◽  
Yield Responses ◽  
Term Field

Details are given on the effect of topdressed phosphorus, at rates up to 60 kg P ha-1, on macronutrient concentrations and phosphorus uptakes of components of white clover based pastures from phosphorus responsive and non-responsive sites. These data were obtained from 17 short-term field experiments conducted over a five year period in south-east Queensland. Plant indices for predicting yield responses to phosphorus by these pastures were derived from nutrient concentrations in tops and in 'diagnostic' samples of white clover collected during spring to early summer. Mathematical approaches used had little effect on critical values obtained. For white clover tops, which comprised fresh leaves, petioles and flowers, a critical phosphorus concentration of from 0.28 to 0.30% was established. Alternatively, an N : P ratio of 15 effectively separated responsive from non-responsive sites. The critical phosphorus concentration based on 'diagnostic' samples, which differed from tops in that flowers were excluded, was 0.30%. There was no practical difference between diagnostic indices based on white clover or total pasture production.

Phosphorus nutrition of peanut (Arachis hypogaea L.) on Cockatoo Sands of the Ord River Irrigation Area

1985 ◽  
Vol 25 (3) ◽  
pp. 649 ◽  
Author(s):  
MJ Bell
Keyword(s):  
Critical Concentration ◽  
Soil Phosphorus ◽  
Maximum Yield ◽  
Dry Weight ◽  
Yield Response ◽  
Phosphorus Concentration ◽  
Irrigation Area ◽  
Arachis Hypogaea L ◽  
Phosphorus Status ◽  
Phosphorus Levels

Yield response of field-grown Virginia Bunch peanuts to a range of soil phosphorus levels, determined using 0.5M NaHCO3 extractant, in the top 10 cm of the soil profile was evaluated on Cockatoo Sands of the Ord River Irrigation Area. Critical levels of soil phosphorus (required to attain 90% of maximum yield recorded in fertilized plots) was 7.3 ppm for pods and 7.9 ppm for kernels. Yield increases obtained with higher soil phosphorus status were due to increased pod number and kernel size. Trends in tissue phosphorus concentration in uppermost fully expanded leaves were monitored during the season, and critical concentrations for 90% of maximum pod yield were derived. The critical concentration (0.30% P, dry-weight basis) did not change with time during the vegetative phase of development, but declined in a linear fashion over time during reproductive development, from 0.27% P at 60 days after emergence to 0.12% P at 100 days after emergence.

Estimation of Soil Phosphorus Levels in Shrimp Ponds

2000 ◽  
Vol 5 (1) ◽  
pp. 115
Author(s):  
G. Ritvo ◽  
M. Sherman ◽  
A. L. Lawrence ◽  
T. M. Samocha
Keyword(s):  
Soil Phosphorus ◽  
Shrimp Ponds ◽  
Phosphorus Levels
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