The P fertilizer requirements of subterranean clover, and the soil P status, sorption and buffering capacities from two P analyses

Soil Research ◽  
1992 ◽  
Vol 30 (1) ◽  
pp. 27 ◽  
Author(s):  
BS Dear ◽  
KR Helyar ◽  
WJ Muller ◽  
B Loveland
Keyword(s):  
Relative Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Phosphorus Concentration ◽  
Phosphorus Sorption ◽  
Phosphorus Fertilizer ◽  
Soil P ◽  
Phosphorus Requirement ◽  
Highly Correlated ◽  
Sorption Curve

The phosphorus fertilizer requirement of subterranean clover (Trifolium subterraneum) was determined on a number of soils in field and glasshouse experiments. The solution phosphorus concentration in a 0.01 M CaCl2 extract (SPC0) determined from a phosphorus sorption curve was found to be closely related (R2 = 0.80 to 0.84) to relative yield. The critical SPC required to achieve 90% of relative yield (SPCc) was 0-128 �g P mL-1 in the field and 0.106 �g P mL-1 in the glasshouse experiments. Phosphorus sorbed at an SPC of 0.10 �g P mL- l (Ps0.1 at SPC0.1) was highly correlated with the phosphorus requirement of subterranean clover in both the field and glasshouse, accounting for 89% and 73% respectively of the variation in phosphorus requirement. A modified two-point sorption curve was found to give a good estimate of phosphorus sorbed at both SPC0.1 (Ps0.1) and SPC0.3(Ps0.3), and greatly increased the number of soil samples that can be processed, compared with a five-point sorption curve. The two-point test involved the addition of solutions containing 0 and 8 �g P mL-1 at a soil: solution ratio of 1:10. The sorption curve constructed using this method was suitable for assessing soils with Ps0.1 levels up to 90 �g P g-1. The soil phosphate buffering capacity at SPC0.1 (PBC0.1) was also accurately estimated using calculations from the two data points, but PBC0.3 values were poorly estimated. It was concluded that the two-point sorption curve is a sensitive and efficient method of predicting the present phosphorus status of clover pastures, their phosphorus fertilizer requirements, and of calculating PBC0.1, a useful soil characteristic.

The effect of time of application of superphosphate on seasonal yield of dry matter from annual pasture

1972 ◽  
Vol 12 (57) ◽  
pp. 392 ◽  
Author(s):  
AA McGowan ◽  
IH Cameron
Keyword(s):  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dry Matter Yield ◽  
Annual Grass ◽  
Time Of Application ◽  
Phosphorus Requirement ◽  
June July

The effect of time of application of superphosphate on the dry matter produced from a subterranean clover (Trifolium subterraneum)annual grass pasture was studied. Treatments involved an annual topdressing of superphosphate, at 125 kg ha-1, in a particular month of the year, for each of the twelve months ; there was also an unfertilized control. In winter, dry matter yield was increased by 350-1190 kg ha-1 when superphosphate was applied at any time of the year. Winter yields were higher after application in January to May (mean 1570 kg ha-1) than in October to December (mean 1190 kg ha-1) or in June-July (mean 1230 kg ha-1). In spring, the greatest increases in dry matter yield were from topdressing in August or September (1600 and 1210 kg ha-1 respectively). Spring yields following application in other months were smaller but usually significantly greater than the yield of unfertilized pasture. The response to autumn application of superphosphate was much greater in winter than in spring. This was not due to a lower phosphorus requirement by the pasture in spring than in winter.

Effects of seed phosphorus concentration on the emergence and growth of subterranean clover (Trifolium subterraneum)

1993 ◽  
Vol 155-156 (1) ◽  
pp. 285-288 ◽  
Author(s):  
C. J. Thomson ◽  
T. P. Bolger
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Phosphorus Concentration

Mineral nutrition of soybeans grown in the South Burnett region of south eastern Queensland. 2. Prediction of grain yield response to phosphorus with soil tests

1983 ◽  
Vol 23 (120) ◽  
pp. 38 ◽  
Author(s):  
PW Moody ◽  
GF Haydon ◽  
T Dickson
Keyword(s):  
Grain Yield ◽  
Buffer Capacity ◽  
Soil Phosphorus ◽  
Maximum Yield ◽  
Relative Yield ◽  
Yield Response ◽  
Phosphorus Concentration ◽  
The South ◽  
Equilibrium Phosphorus Concentration ◽  
Highly Correlated

Grain yield response of soybean (Glycine max cv. Bragg) to applied phosphorus was measured at 19 experimental sites in the South Burnett region. The soil phosphorus supply factors of quantity, intensity, buffer capacity and rate were estimated by various soil chemical tests, and relative yield [(yield at nil applied phosphorus/maximum yield) x 100] regressed against these tests. The equilibrium phosphorus concentration-the intensity measure-accounted for the greatest percentage variation in relative yield (80%) and at 90% maximum yield was 0.014 �g P/ml. Phosphorus extracted by 0.01 M CaCl2 was highly correlated with the equilibrium phosphorus concentration (r2=0.93) and accounted for 73% of the variation in relative yield. Soil levels of calcium chloride-extractable phosphorus were interpreted as follows: < 0.044 �g P/g, response to phosphorus probable; 0.044 �g P/g to 0.058 �g P/g, response uncertain; > 0.058 �g P/g, response unlikely

Factors contributing to reduced productivity of subterranean clover (Trifolium subterraneum L.) pastures on acidic soils

1990 ◽  
Vol 41 (4) ◽  
pp. 669 ◽  
Author(s):  
Z Hochman ◽  
GJ Osborne ◽  
PA Taylor ◽  
B Cullis
Keyword(s):  
Seed Production ◽  
Root Rot ◽  
Seedling Survival ◽  
Soil Phosphorus ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Phosphorus Sorption ◽  
Sorption Index ◽  
Clover Seed ◽  
Root Health

In a field study on four sites, soil acidity, root rot (Phytophthora clandestina), and soil phosphorus were identified as causes of 'subterranean clover decline'. Liming increased herbage and seed production at four sites, with a tendency for lime to increase herbage yields in autumn (22%) and winter (15%) but not in spring. The presence of ryegrass with clover increased total herbage yields, and reduced clover seed production, but there was no interaction with liming. Losses caused by root rot associated with P. clandestina were quantified for the first time in New South Wales. Root rot reduced survival of seedlings as well as herbage production in autumn and/or winter at three of the four sites. In the presence of the disease, lime did not improve root health or seedling survival. On two sites with high aluminium saturation of exchangeable cations (> 17%) and high phosphorus sorption index values, subterranean clover growth responded to high levels of P fertilizer. On one site, where lime increased the soil pH to above 5.5, the P sorption index was temporarily increased, and this was associated with a temporary adverse effect on herbage yields. Some possible mechanisms underlying the seasonality of lime responses are proposed and the practical implications of our findings are discussed.

Field evaluation of a leaf test for assessment of the phosphorus status of subterranean clover and for prediction of its response to phosphorus

1985 ◽  
Vol 25 (2) ◽  
pp. 331 ◽  
Author(s):  
EJ Dowling ◽  
D Bouma
Keyword(s):  
Field Experiments ◽  
Relative Yield ◽  
Leaf Tissue ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Field Evaluation ◽  
Close Relation ◽  
Critical Value ◽  
Late Winter ◽  
Phosphorus Status

A series of field experiments (5 phosphorus levels x 6 replicates) on the southern Tablelands of New South Wales was used, firstly, to confirm the suitability of a modified test for inorganic phosphorus (Pi) concentrations in fresh clover (Trifolium subterraneum) leaves as an index of the current phosphorus status of subterranean clover-based pastures; and, secondly, to evaluate the usefulness of Pi as a predictor of responses to phosphorus applications. A close relation (R2 = 0.910) was found between Pi in healthy green leaf tissue sampled in winter and field responses to phosphorus measured at the same time. The fitted curve had a critical value of 154 ppm Pi at 90% of the fitted asymptote for relative yield. Close relations were also found between total herbage yield measured over the season and Pi in leaf tissue sampled in late autumn and early winter (R2 = 0.896) and in leaves sampled in late winter and early spring (R2= 0.877). Critical values were 160 and 153 ppm Pi respectively. The relation was less close for the third sampling (seed set and flowering, R2= 0.809) and the critical value had declined to 118 ppm Pi. It is concluded that Pi determined in clover leaf samples provides a simple measure of the current phosphorus status of subterranean clover-based pasture, and of its likely response to phosphorus. A critical value of 150 ppm Pi is confirmed for assessing the current phosphorus status, and is also proposed for predictive purposes. The method described for the estimation of Pi is a further simplification of the method presented previously. It is also more rapid and achieves a saving of 80-90% in chemicals. The correlation coefficient for the straight line relationship between the two methods was 0.956 (68 observations).

Herbicide dose rate response curves in subterranean clover determined by a bioassay

1997 ◽  
Vol 37 (1) ◽  
pp. 67 ◽  
Author(s):  
G. A. Sandral ◽  
B. S. Dear ◽  
J. E. Pratley ◽  
B. R. Cullis
Keyword(s):  
Dose Rate ◽  
Field Tests ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Response Curves ◽  
Leaf Stage ◽  
Time Of Application ◽  
Herbicide Treatments ◽  
Highly Correlated ◽  
Major Factors

Summary. Herbicide dose response curves were developed for 5 herbicide treatments, MCPA, 2,4-DB, bromoxynil, MCPA + terbutryn and MCPA + diuron, when applied to 2 cultivars of subterranean clover (Trifolium subterraneum L.) in a glasshouse experiment. The effect of varying spraying time (14 May and 14 June) and leaf stage (3–4 v. 8–10 trifoliate leaves) at spraying was also examined. The dose rate multiple of the recommended rate required to reduce the clover herbage yield by 50% (I50) differed markedly between herbicide treatments. The 2 MCPA mixtures were the most phytotoxic with an I50 value between 0.45 and 0.83, bromoxynil and MCPA alone were intermediate. 2,4-DB was the least phytotoxic with an I50 value between 2.36 and 2.94 depending on cultivar and leaf stage at the time of application. The effect of leaf stage at spraying, time of spraying and cultivar on herbicide phytotoxicity was relatively small, the major factors being herbicide choice (which accounted for 83% of the variation in I50 values) and rate of herbicide applied. While there was differential cultivar tolerance to the herbicide 2,4-DB, there was no difference between the cultivars in their response to the other herbicide treatments. The phytotoxicity of the herbicides applied at either the 3–4 or 8–10 leaf stage in the glasshouse bioassay was highly correlated (r = 0.84, P<0.01) with previous estimates of phytotoxicity determined under field conditions, although slightly overestimated phytotoxicity compared with field tests. European Weed Research Council (EWRC) scores of herbicide damage in the glasshouse bioassay were found to be highly negatively correlated with dry matter yield losses in both the glasshouse (r = –0.78 to –0.98, P<0.001) and field (r = –0.72, P<0.001) and are therefore an acceptable alternative where destructive sampling is not practical. The EWRC scoring system was found to be more effective at quantifying damage where it was manifest as burning or stunting rather than as leaf distortion. The study indicated that a glasshouse herbicide bioassay is a useful technique for rapidly screening herbicides for phytotoxicity on subterranean clover.

Evaluation of phosphorus in savannah soils of western Nigeria under bush fallow systems

1983 ◽  
Vol 101 (2) ◽  
pp. 283-289 ◽  
Author(s):  
O. J. Ayodele ◽  
A. A. Agboola
Keyword(s):  
Organic Matter ◽  
Relative Yield ◽  
Maize Yield ◽  
Available P ◽  
Yield Response ◽  
Phosphorus Sorption ◽  
Direct Role ◽  
Soil P ◽  
Fallow Systems ◽  
Total P

SUMMARYYield calibration of soil tests in western Nigeria savannah has been difficult owing to low response to P and response to only low P rates despite low available P in the soils. A study on the distribution of P forms in 60 surface soils of the savannah derived from igneous and metamorphic rocks and grouped into 11 classes was made. Average total P was 0·018% and organic P, which varied between 44 and 114 mg/kg, constituted 41% of total P. Active P components made up 40% of total inorganic P, the bulk of which was in the Fe-P fraction. All P forms except non-extractable P correlated significantly with organic matter.The amounts of P needed to increase available P by 1 mg/kg in the soils, an index of P fixation, was correlated with pH and the free oxides of Fe and Al. The direct role of Fe-oxides and probable indirect effect of organic matter were indicated by regression analysis.There was minimal maize yield response to P application and this was obtained only at low P rates from which an optimum rate of 20 kg P/ha was suggested. An attempt to use phosphorus sorption capacity (PSC) for P recommendation was not successful probably because of the low PSC values. A quick P recommendation based on available P status, fertilizer factor of 3·0 mg/1 and an optimum available P level derived from the relative yield v. soil P calibration curve was therefore suggested.

Sulfur requirements during early growth of Trifolium balansae, Trifolium subterraneum, Medicago murex, and Phalaris aquatica

1995 ◽  
Vol 35 (2) ◽  
pp. 199 ◽  
Author(s):  
A Pinkerton ◽  
PJ Randall
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Early Growth ◽  
Critical Values ◽  
Sand Culture ◽  
Published Data ◽  
Phalaris Aquatica ◽  
Critical Concentrations ◽  
Highly Correlated ◽  
Nutrient Solutions

Sulfur (S) requirements for early growth were determined for 3 legumes (Trifolium balansae, T. subterraneum, Medicago murex) and 1 grass (Phalaris aquatica). Plants were grown in sand culture in a glasshouse and supplied with nutrient solutions containing 6 rates of S (1-32 �g/mL). Legumes were supplied with nitrogen (N) at 168 �g/mL, and phalaris with 28 or 168 pg N/mL. Plants were sampled twice, the second sampling coinciding with flowering of the legumes. Diagnostic indices [total S (St), HI-reducible S (sulfate-S), oxidised S (S6+)], and ratios (sulfate-S/St, S6+/St) were derived for whole shoots (WS), youngest open leaves (YOL) of legumes, and youngest expanded blades (YEB) of the grass. The largest responses to S by the legumes were made by balansa clover and murex medic, which both outyielded subterranean clover, but subterranean clover was the most efficient user of S and had the lowest external S requirement. Concentrations of S6+ were always higher than concentrations of sulfate-S, but the 2 were highly correlated and much lower than St. No S fraction or plant part sampled was consistently superior as an indicator of S status. The larger relative increases and sharper breaks in gradient of the relationships between yield and sulfate-S or S6+ compared with St were offset by their greater relative variability. All indices were subject to Piper-Steenbjerg effects, although these did not seriously affect the critical values. Critical values of St and S6+ in YOL, St in WS of balansa clover, and S, and S6+ in WS of subterranean clover changed little up to 60 days after sowing, but it was necessary to know plant age when assessing the S status of murex medic or phalaris. Critical concentrations of S, in phalaris were little affected by N supply, but critical concentrations of sulfate-S and S6+ were higher with 28 than 168 �g N/mL. Critical values for subterranean clover agreed well with previously published data.

Effect of cultivar and grazing intensity in spring on shear and compression energies of dry mature subterranean clover (Trifolium subterraneum L.)

1997 ◽  
Vol 48 (8) ◽  
pp. 1199 ◽  
Author(s):  
Y. J. Ru ◽  
J. A. Fortune
Keyword(s):  
Flowering Time ◽  
Large Range ◽  
Grazing Intensity ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Plant Materials ◽  
Leaf Petiole ◽  
Dry Matter Digestibility ◽  
Highly Correlated ◽  
Shear Energy

Twenty-six cultivars of subterranean clover were divided into 3 maturity groups according to the flowering time and sown in 2 blocks with 4 replicates. The plots were grazed under 2 intensities (hard and lax) during the growing season. The proportions of leaf, petiole, stem, and burr before senescence, dry matter digestibility (DMD), herbage availability, and seed yield in summer were measured. The energies required to shear and compress the resultant dry mature plant materials were determined using an Instron material testing instrument. The results showed a large range for shear (11·3-18·2 kJ/m2) and compression energies (2·8-4·6 kJ/kg DM) among the 26 cultivars. Grazing intensity in spring did not affect shear energy (P > 0·05) but increased the compression energy of dry mature subterranean clover by 0·2 units (P < 0·05). The energy required to shear or compress plant materials was highly correlated with herbage availability, flowering time, proportions of leaf and petiole in the sward, and fibre content of the plant materials, with the relationships being modified by grazing intensity in spring. Compression energy was related to DMD of plants (r = -0·7) and shear energy did not account for a significant amount of variation in DMD.

Sign in / Sign up

Export Citation Format

Share Document