Response of spring-planted lettuce (Lactuca sativa L.) to freshly-applied and residual phosphorus and to phosphate fertiliser placement on a Karrakatta sand

1997 ◽  
Vol 37 (6) ◽  
pp. 701
Author(s):  
W. J. Robertson ◽  
I. R. McPharlin
Keyword(s):  
Lactuca Sativa ◽  
Maximum Yield ◽  
Relative Yield ◽  
P Uptake ◽  
Soil Test ◽  
Recovery Efficiency ◽  
Lactuca Sativa L ◽  
Phosphate Fertiliser ◽  
Soil Test P ◽  
Whole Plants

Summary. The phosphorus (P) requirements of crisphead lettuce (Lactuca sativa L. cv. Salinas) were measured over 2 consecutive spring plantings using superphosphate that was freshly applied and applied 9 months before planting, at 0–600 kg P/ha on a newly-cleared Karrakatta sand of low natural P fertility. The response of lettuce to placement of phosphate fertiliser (banded, broadcast) was also investigated. There was a significant (P<0.001) head yield response to level of applied P in all experiments. There was no significant effect of placement on yield even though the concentrations of P in the wrapper leaves were on average 12% higher in the broadcast treatment. A Mitscherlich function described the relationship of P uptake by whole plants and plant shoots to level of applied P. Recovery efficiency of P fertiliser (fertiliser P uptake by shoots/P applied, both in kg/ha) by shoots decreased from 0.12 at 50 to 0.05 at 600 kg applied P/ha. Phosphorus recovery efficiency by whole plants (shoots plus roots) decreased from 0.13 at 50 to 0.05 at 600 kg P/ha. The level of freshly-applied P required for 95 and 99% of maximum relative yield over the 2 years (maximum yield, 89–112 t/ha) was 185 and 286 kg P/ha (Mitscherlich relationship, R2 = 0.93), respectively, at <10 µg/g soil test P (newly-cleared sites). The marketable yield was 82 and 92% of total yield at 185 and 286 kg P/ha respectively. Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on residual P sites over 2 years where P was applied at 0–600 kg/ha. These soil test levels were related to head yield in a Mitscherlich relationship (R2 = 0.90). The critical soil test P values required for 95 and 99% of maximum relative yield, over the 2 years, were 81 and 121 µg/g respectively. Phosphorus in the wrapper leaf at early heading required for 95 and 99% of maximum yield was 0.40 ± 0.02 and 0.42 ± 0.02% (spline regression, R2 = 0.81), respectively. Soil and plant testing could be used to assist in reducing fertiliser costs, improving the efficiency of use of freshly- and previously-applied fertiliser P by lettuce and reducing P losses to water systems on the Swan Coastal Plain in Western Australia. Changing placement from broadcasting to banding will not improve efficiency of phosphate fertiliser use by lettuce on Karrakatta sands.

Phosphorus requirements of winter-planted lettuce (Lactuca sativa L.) on a Karrakatta sand and the residual value of phosphate as determined by soil test

1996 ◽  
Vol 36 (7) ◽  
pp. 897 ◽  
Author(s):  
IR McPharlin ◽  
RC Jeffery ◽  
DH Pitman
Keyword(s):  
Lactuca Sativa ◽  
Maximum Yield ◽  
Relative Yield ◽  
Phosphorus Recovery ◽  
Yield Response ◽  
Soil Test ◽  
Recovery Efficiency ◽  
Lactuca Sativa L ◽  
Soil Test P ◽  
Whole Plants

The phosphorus (P) requirements of crisphead lettuce (Lactuca sativa L. cv. Oxley) was measured over 2 consecutive winter plantings using superphosphate that was freshly applied and applied 9 months before planting, at 0-600 kg/ha on a newly cleared Karrakatta sand of low natural P fertility. There was a significant (P<0.001) head yield response to level of applied P in both years. Phosphorus uptake by whole plants and plant shoots was related to level of applied P in Mitscherlich relationships (R2 = 0.88). Phosphorus recovery efficiency (fertiliser P uptake by shoots/P applied, both in kg/ha) by shoots decreased from 0.16 at 50 to 0.04 at 600 kg applied P/ha. Phosphorus recovery efficiency by whole plants (shoots plus roots) decreased from 0.18 at 50 to 0.05 at 600 kg P/ha. The level of freshly applied P required for either 95 or 99% of maximum relative yield over the 2 years (maximum yield, 86 t/ha) was 276 and 427 kg P/ha (Mitscherlich relationship, R2 = 0.95), respectively at <10 �g/g soil test P (newly cleared sites). The marketable yield was 82 and 95% of total yield at 276 and 427 kg P/ha respectively. Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on residual P sites over 2 years where P was applied at 0-600 kg/ha. These soil test levels were related to head yield in a Mitscherlich relationship (R2 = 0.88). The critical soil test P values required for either 95 or 99% of maximum relative yield, over the 2 years, were 80 and 115 �g/g, respectively. Phosphorus in the wrapper leaf at early heading required for 95 or 99% of maximum yield was 0.59 � 0.03 and 0.61 � 0.03% (spline regression, R2 = 0.80), respectively. Soil and plant testing could be used to assist in reducing fertiliser costs, improving utilisation of freshly- and previously-applied fertiliser P by lettuce and reducing P losses to water systems on the Swan Coastal Plain in Western Australia.

Response of onions (Allium cepa L.) to phosphate fertiliser placement and residual phosphorus on a Karrakatta sand

1999 ◽  
Vol 39 (3) ◽  
pp. 351 ◽  
Author(s):  
W. J. Robertson ◽  
I. R. McPharlin
Keyword(s):  
Maximum Yield ◽  
Relative Yield ◽  
P Uptake ◽  
Soil Test ◽  
Recovery Efficiency ◽  
Mature Leaves ◽  
Phosphate Fertiliser ◽  
Allium Cepa L ◽  
Soil Test P ◽  
Bulb Yield

The phosphorus (P) requirement of irrigated onions (Allium cepa L. cv. Creamgold) was measured over 2 consecutive spring plantings using superphosphate that was freshly-applied and applied 9 months before planting, at 0–800 kg P/ha on a newly cleared Karrakatta sand of low natural P fertility. The response of onions to placement of phosphate fertiliser (banded or broadcast) was also investigated. There was a significant (P<0.001) bulb yield response to level of applied P in all experiments. There was no significant effect of placement on yield although the concentrations of P in the youngest mature leaves and bulbs were on average 18% higher (i.e. 0.40 v. 0.34%) than in the broadcast treatment. A rectangular hyperbola described the relationship of P uptake by shoots or bulbs to level of applied P. Recovery efficiency (RE) of fertiliser P (P uptake by bulbs at rate i of applied P – uptake in absence of applied P/rate i of applied P) by bulbs after curing decreased from 0.43 at 50 kg P/ha to 0.06 at 600 kg P/ha. Recovery efficiency by bulbs at applied P required for 95 and 99% of maximum yield was 0.20 and 0.14 respectively. The level of freshly-applied P required for 95 and 99% of maximum relative yield over the 2 years (maximum yield, 80–100 t/ha) was 122 and 203 kg P/ha (Mitscherlich relationship, R2 = 0.82), respectively, at <10 g/g Colwell P soil test (newly cleared sites). The marketable (total – reject) yield was 94% and 92% of total yield at 122 and 203 kg P/ha respectively. Bicarbonate-soluble P extracted from the top 15 cm of soil was determined on residual P sites over 2 years where P was applied at 0–800 kg/ha. These soil test levels were related to bulb yield in a Mitscherlich relationship (R2 = 0.90). The critical soil test P values required for 95 and 99% of maximum relative yield, over the 2 years, were 50 and 80 g/g respectively. Phosphorus in the youngest mature leaves required for 95 and 99% of maximum yield ranged from 0.22–0.28 to 0.26–0.32%, respectively, from the Mitscherlich regressions, depending on plant stage (i.e. leaf number or days after sowing) although there was no consistent trend with age. Soil testing can be used to reduce current applications of fertiliser P without reducing yield. Plant testing can be used to monitor the P status and associated fertiliser needs of onions on sands. Both these testing procedures need to be verified in commercial crops with a wide variation in soil test P levels and management practices. Soil and plant testing could therefore be used to reduce fertiliser application and cost, improve fertiliser RE by onions and reduce fertiliser P losses to water systems on the Swan Coastal Plain. Changing placement from broadcasting to banding does not appear to improve the efficiency of phosphate fertiliser use by irrigated onions on Karrakatta sands.

scholarly journals 650 PB 022 DIFFERENT LETTUCE TYPES RESPOND SIMILARLY TO P FERTILIZATION

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 525g-526
Author(s):  
N.M. El-Hout ◽  
C.A. Sanchez
Keyword(s):  
Field Experiments ◽  
Maximum Yield ◽  
Relative Yield ◽  
Yield Potential ◽  
Soil Test ◽  
P Fertilization ◽  
Yield And Quality ◽  
Large Yield ◽  
Soil Test P ◽  
The Relationship

The production of lettuce (Lactuca sativa L.) types other than crisphead (i.e., leaf, boston, bibb, and romaine) has recently increased due to expanding consumer demand. Fertilizer P recommendations for these lettuce types are largely based on soil-test calibrations for the crisphead type only. However, biomass production and morphological traits of the different lettuce types vary. Four field experiments were conducted to compare the relative efficiencies of these lettuce types to P fertilization. All lettuce types showed large yield and quality responses to P. Because environmental conditions affected yield potential, P rates required for optimal yield varied by lettuce type within experiments. However, the P rates required for optimal yield were similar over all experiments. Furthermore, the relationship between relative yield and soil-test P across all seasons showed a similar soil-test P level was required for maximum yield of all lettuce types. The results of this study show that soil-test-based fertilizer recommendations for crisphead lettuce may be adequate for all lettuce types

scholarly journals Response of Diverse Lettuce Types to Fertilizer Phosphorus

HortScience ◽  
1995 ◽  
Vol 30 (3) ◽  
pp. 528-531 ◽  
Author(s):  
C.A. Sanchez ◽  
N.M. El-Hout
Keyword(s):  
Field Experiments ◽  
Maximum Yield ◽  
Relative Yield ◽  
Yield Potential ◽  
Soil Test ◽  
P Fertilization ◽  
Large Yield ◽  
Soil Test P ◽  
Southern Florida ◽  
Index Level

Four field experiments were conducted from 1990 to 1992 on Histosols in southern Florida to compare the relative response of various types of lettuce (Lactuca sativa L.) (i.e., leaf, Boston, Bibb, romaine, and crisphead lettuce) to P fertilization. All lettuce types showed large yield and quality responses to P fertilization. Because environmental conditions affected yield potential, P rates required for optimal yield varied for lettuce types across experiments. However, with the exception of Boston, the P rates required for optimal yield were similar when averaged over all experiments. Furthermore, the relationship between relative yield and soil-test P across all seasons showed that a similar soil-test P index level was required for maximum yield of all lettuce types. Overall, the results of this study suggest that existing soil-test-based fertilizer recommendations for crisphead lettuce are adequate for other lettuce types currently grown.

scholarly journals Pengaruh Penambahan Ca(NO3)2 Terhadap Hasil Tanaman Selada Kriting (Lactuca Sativa L.) pada Sistem Hidroponik Deep Flow Technique (DFT)

2020 ◽  
Vol 10 (2) ◽  
pp. 190
Author(s):  
NI NYOMAN SURYANTINI ◽  
GEDE WIJANA ◽  
RINDANG DWIYANI
Keyword(s):  
Lactuca Sativa ◽  
Maximum Yield ◽  
Calcium Nitrate ◽  
Vegetable Crops ◽  
Hydroponic System ◽  
Lactuca Sativa L ◽  
Deep Flow Technique ◽  
The Moment ◽  
Require Composition ◽  
Nutrient Solutions

The Effect of Addition of Ca(NO3)2 to the Results of Lettuce (Lactuca sativa L.) in the Hydroponic System of Deep Flow Technique (DFT). Plants, in general, require composition, concentration, and volume of nutrient solutions which different depends on the type and phase of plant growth. Leaf vegetable crops such as lettuce (Lactuca sativa L.) require higher Nitrogen (N) nutrients than other vegetable crops, but the problem we faced at the moment is the hydroponic nutrients that are traded only in the general form of nutrient, therefore the addition of N nutrients in the form of calcium nitrate (Ca(NO3)2) needs to be done to meet the needs of lettuce plants. This study was aimed to determine the effect of the addition of Ca(NO3)2 and to find the optimum dosage of the addition of Ca(NO3)2 to the general hydroponic nutrition of vegetables on lettuce use DFT hydroponic system. The treatments consisted of five levels which are nutrition AB Mix general vegetable as a control, and nutrition AB Mix with the addition of 30 g, 60 g, 90 g, and 120 g Ca(NO3)2.  The results of the observation showed that the treatment of the addition of Ca(NO3)2 fertilizer had a very significant effect on all observed variables, except for the diameter of the lettuce plant. The optimum addition of Ca(NO3)2 for lettuce was found at 90.04 g with a maximum yield of 207.92 g.

Phosphate fertiliser residues in wheat-growing soils of the Western Downs, Queensland

Soil Research ◽  
1997 ◽  
Vol 35 (2) ◽  
pp. 341 ◽  
Author(s):  
W. M. Strong ◽  
E. K. Best ◽  
J. E. Cooper
Keyword(s):  
Field Experiments ◽  
Moisture Stress ◽  
P Uptake ◽  
Residual Effects ◽  
Wheat Crop ◽  
Soil Test ◽  
Phosphate Fertiliser ◽  
Plant Moisture ◽  
Field Plots ◽  
Extractable Soil

Effects of repeated annual application and residual effects of past phosphorus (P) applications were studied at Billa Billa and The Gums, Queensland, on 2 Vertisols representative of a large cropping area in this region. Phosphorus was applied annually at 0, 4, 8, 12, and 25 kg/ha at sowing to each wheat crop between 1978 and 1988. Phosphorus was also applied at 25, 50, 100, 200, or 400 kg/ha as a once-only application, before wheat was sown in 1978, and was incorporated by tillage. Pot experiments were conducted each year with soil (6 kg/pot) gathered from field plots in May before wheat sowing to determine the residual value (RV) of previously applied P fertiliser under standard conditions of frequent watering. In 1979 the RV was determined in a second series of pots with a water deficit to simulate conditions of plant moisture stress that were to dominate the field experiments. The RV of P fertiliser was reduced to one-third that determined under well-watered conditions. Low residual values (8–47%) determined in the field in 1979 for P rates 25 and 50 kg/ha applied in 1978 were probably due to reduced P uptake from dry topsoil throughout which P residues were incorporated by tillage. By contrast, P applied annually at a low rate (4 or 8 kg/ha) in a band close to seeds created profitable responses when evaluated over the sequence of successive wheat crops. The bicarbonate-extractable soil test value (Pbf) on either soil fertilised annually for n years with P at a rate R (kg/ha· year) was described by the model where Pbu is the soil test value (mg/kg) of unfertilised soil.

scholarly journals COMPORTAMENTO DA ALFACE-AMERICANA SOB DIFERENTES DOSES DE COMPOSTO ORGÂNICO E LÂMINAS DE IRRIGAÇÃO(I)

Irriga ◽  
2018 ◽  
Vol 22 (1) ◽  
pp. 167-176 ◽  
Author(s):  
Kenya Gonçalves Nunes ◽  
Raimundo Nonato Távora Costa ◽  
José Aglodualdo Holanda Cavalcante Júnior ◽  
Danielle Ferreira de Araújo
Keyword(s):  
Lactuca Sativa ◽  
Water Productivity ◽  
Maximum Yield ◽  
Production Factor ◽  
Quadratic Model ◽  
Production Factors ◽  
Lactuca Sativa L ◽  
Lettuce Yield ◽  
Irrigation Levels ◽  
Different Levels

COMPORTAMENTO DA ALFACE-AMERICANA SOB DIFERENTES DOSES DE COMPOSTO ORGÂNICO E LÂMINAS DE IRRIGAÇÃO(I)  KENYA GONÇALVES NUNES1; RAIMUNDO NONATO TÁVORA COSTA1; JOSÉ AGLODUALDO HOLANDA CAVALCANTE JÚNIOR2 E DANIELLE FERREIRA DE ARAÚJO3 (I)Parte da dissertação de mestrado do primeiro autor.1Universidade Federal do Ceará, Departamento de Engenharia Agrícola, Fortaleza-CE, [email protected], [email protected] Federal de Educação do Ceará, Crateús-CE, [email protected] de Fortaleza, Fortaleza-CE, [email protected]  1 RESUMO A alface é uma das hortaliças mais cultivadas em várias regiões brasileiras e com a crescente demanda de produtos orgânicos pelos consumidores, vários produtores decidiram migrar para o método ecológico de cultivo. O estudo teve como objetivo avaliar a capacidade produtiva da alface sob diferentes tratamentos de lâminas de irrigação e doses de composto orgânico. Utilizaram-se cinco lâminas de irrigação e quatro doses de composto orgânico em um delineamento experimental em blocos inteiramente casualizados, no esquema de parcelas subdivididas e quatro repetições. Os resultados permitiram concluir que: a aplicação dos fatores de produção água e composto orgânico elevaram os níveis médios de produtividade da alface em até 38,3%; a produtividade máxima estimada pode ser obtida com dose 6,3 kg m-2 de composto orgânico; o decréscimo inferior a 6% no nível de produtividade média da alface ao se reduzir em 50% a lâmina de irrigação aplicada demonstra que este fator de produção, além de não ter sido limitante, possibilita o uso da estratégia de irrigação com déficit; os valores médios de produtividade da água incrementaram com o aumento das doses de composto orgânico segundo um modelo quadrático. Palavras-chave: Lactuca sativa L., adubação orgânica, controle da irrigação.  NUNES, K. G.; COSTA, R. N. T.; CAVALCANTE JÚNIOR, J. A. H.; ARAÚJO, D. F.HEAD LETTUCE BEHAVIOR UNDER DIFFERENT LEVELS OF ORGANIC COMPOST AND IRRIGATION  2 ABSTRACT Lettuce is one of the vegetables cultivated in several regions and nowadays it is easy to see an increase in demand for organic products by consumers, many producers decided to change and start to produce with a new method of cultivation called organic farming. This study aimed to investigate the lettuce yield under different levels of irrigation and compost. It were used five irrigation levels and four different applications of compost. The experimental design was a randomized block in a split-plot with four replications scheme. The results of this study led to the following conclusions: the application of water and compost as production factors allowed raising the average levels of lettuce yield of up to 38.3%; it is possible to obtain the maximum yield with a level of compost equivalent to 6.3 kg m-2; it was observed a decrease lower than 6% in the average level of lettuce productivity when the depth was reduce by 50%, this result shows that this production factor it is not limiting, and it is possible to use an irrigation strategy with deficit; the average values of water productivity grown with the increase in the levels of compost according to a quadratic model. Keywords: Lactuca sativa L., organic fertilization, irrigation control.

RELATING SOIL TEST P TO P UPTAKE BY PADDY RICE

Soil Science ◽  
1995 ◽  
Vol 159 (6) ◽  
pp. 409-414 ◽  
Author(s):  
Y. H. TEO ◽  
C. A. BEYROUTY ◽  
E. E. GBUR
Keyword(s):  
P Uptake ◽  
Paddy Rice ◽  
Soil Test ◽  
Soil Test P

Using soil testing and petiole analysis to determine phosphorus fertiliser requirements of potatoes (Solanum tuberosum L. cv. Delaware) in the Manjimup-Pemberton region of Western Australia

2000 ◽  
Vol 40 (1) ◽  
pp. 107 ◽  
Author(s):  
M. A. Hegney ◽  
I. R. McPharlin ◽  
R. C. Jeffery
Keyword(s):  
Solanum Tuberosum ◽  
Tuber Yield ◽  
Solanum Tuberosum L ◽  
Maximum Yield ◽  
Soil Testing ◽  
Yield Response ◽  
Soil Test ◽  
Versus Level ◽  
Soil Test P ◽  
The Relationship

Field experiments were conducted over 3 years at 21 sites of varying phosphorus (P) fertiliser histories (Colwell P range: 9–170 g/g) in the Manjimup–Pemberton region of Western Australia to examine the effects of freshly applied (current) and previously applied (residual or soil test ) P on the yield of potatoes (Solanum tuberosum L. cv. Delaware). Phosphorus was placed (banded) at planting, 5 cm either side of and below seed planted at 20 cm depth, at levels up to 800 kg P/ha. Exponential [y = a – b exp (–cx)] regressions were fitted to the relationship between tuber yield and level of applied P at all sites. Weighted (according to the variance) exponential regressions were fitted to the relationship between yield responsiveness (b/a, from the yield versus level of applied P relationship) and Colwell P, and two P sorption indices—phosphate adsorption (P-adsorb) and a modified phosphate retention index (PRI(100)). A weighted exponential regression was also fitted to the relationship between the level of applied P required for 95% of maximum yield (Popt; also from yield versus level of applied P) and P-adsorb and PRI(100). A weighted linear regression best described the relationship between Popt and Colwell P. Phosphorus application significantly (P<0.10; from the regression analysis) increased total tuber yield at all but 4 sites. Marketable tuber yield response paralleled total tuber yield response at all sites and averaged 85% of total yields (range 63–94%). Colwell P gave a good prediction of the likely yield response of potatoes across all sites. For example, the yield responsiveness (b/a) of potatoes in relation to Colwell P decreased exponentially from 1.07 at 0 g/g to 0, or no yield response, at 157 g/g Colwell P (R2 = 0.96) i.e. the critical Colwell P for 95% of maximum yield of potatoes on soils in the Manjimup–Pemberton region. Similarly, no yield response (b/a = 0) would be expected at a P-adsorb of 180 g/g (R2 = 0.69) or a PRI(100) of 46 (R2 = 0.61). The level of applied P required for 95% of maximum yield (Popt) decreased linearly from 124 kg/ha on infertile sites (<5 g/g Colwell P) to 0 kg P/ha at 160 g/g Colwell P (R2 = 0.66). However, a more accurate prediction of Popt was possible using either P-adsorb or PRI(100). For example, Popt increased exponentially from 0 kg/ha at <181 g/g P-adsorb (high P soils) to 153 kg/ha at a P-adsorb of 950 g/g (low P soils) (R2 = 0.75) and exponentially from 0 kg/ha at a PRI(100) of <48 (high P soils) to 147 kg/ha at a PRI(100) of 750 (low P soils) (R2 = 0.80). PRI(100) is preferred as a soil test to predict Popt for potatoes in the Manjimup–Pemberton region because of its superior accuracy to the Colwell test. It is also preferred to P-adsorb because of both superior accuracy and lower cost as it is a simpler and less time consuming procedure — features which are important for adoption by commercial soil testing services. A multiple regression including Colwell P, P-adsorb and PRI(100) only improved the prediction of Popt slightly (R2 = 0.89) over PRI(100) alone. When tubers were 10 mm long, the total P in petioles of youngest fully expanded leaves which corresponded with 95% of maximum yield was 0.41% (dry weight basis). These results show that, while the Colwell soil P test is a useful predictor of the responsiveness of potato yield to applied P across a range of soils in the Manjimup–Pemberton region, consideration of both the soil test P value and the P sorption capacity of the soil, as determined here by PRI(100), is required for accurate predictions of the level of P fertiliser required to achieve maximum yields on individual sites.

Response of winter-grown potatoes (Solanum tuberosum L.) to applied and residual phosphorus on a Karrakatta sand

1997 ◽  
Vol 37 (1) ◽  
pp. 131
Author(s):  
M. A. Hegney ◽  
I. R. McPharlin ◽  
R. C. Jeffery
Keyword(s):  
Solanum Tuberosum ◽  
Tuber Yield ◽  
Solanum Tuberosum L ◽  
Total Yield ◽  
Maximum Yield ◽  
Dry Weight ◽  
Phosphorus Recovery ◽  
Soil Test ◽  
Residual P ◽  
Soil Test P

Summary. The response of winter-grown potatoes (Solanum tuberosum L. cv. Delaware), as determined by yield, to applied (broadcast) phosphorus (P) (0–480 kg/ha) and to residual P was measured on an acutely P-deficient, newly cleared Karrakatta sand in experiments over 2 years. Tuber yield responded significantly (P<0.001) to level of applied P. Phosphorus at 162 kg/ha was necessary for 99% of maximum total yield, which corresponded to maximum economic yield. For 95% of maximum yield 99 kg/ha was necessary. Phosphorus recovery efficiency by tubers (P uptake by tubers/P applied, both in kg/ha) decreased from 0.14 at 30 kg P/ha to 0.04 at 480 kg P/ha. Bicarbonate-soluble P (soil test P) extracted from the top 15 cm of soil was determined on residual P sites in each experiment to which P was applied (as superphosphate) 9 months earlier at levels from 0 to 800 kg/ha. These soil test P levels were related (R2 = 0.91) to total tuber yield. The soil test P level required for 95% of maximum total yield was 33 g/g and for 99% was 51 µg/g. When tubers were 10 mm long, the total P in petioles of youngest fully expanded leaves which corresponded to 95% of maximum yield was 0.7% (dry weight basis), and for 99% was 0.87%. These results, while based on responses measured at 2 sites only, provide strong evidence that maximum yield of winter-grown potatoes on Karrakatta sands can be achieved with lower levels of P fertiliser than are currently used in commercial practice (125–300 kg P/ha). The results also show that soil testing can be used to improve the P management of potato crops grown on the sandy soils of the Swan coastal plain.

Sign in / Sign up

Export Citation Format

Share Document