Influence of soil organic carbon on the interpretation of soil test P for wheat grown on alkaline soils
Tóm tắt
Organic carbon is known to alter crop response to applied phosphorus (P) but that fact has not been incorporated in soil test interpretations. To achieve this objective, field experiments with wheat were conducted for four years on alkaline soils of Punjab, India. The experimental soils ranged from loamy sand to loam in texture, 7.4 to 9.6 in pH, 0.16 to 0.75% in organic carbon (OC) and 2 to 40 mg Olsen extractable P kg−1 soil. Response of wheat to fertilizer phosphorus application was related to the combined effect of Olsen P and soil OC content. At a given Olsen P level, wheat yield was a function of soil OC content. Multiple regression analysis of the data showed that OC content <0.2% did not affect yield significantly. At values >0.6%, OC along with Olsen P accounted for 97% of the variation in yield and there was no response to applied fertilizer P. Yield isoquants for 4 and 5 tons grains ha−1 showed that for a given Olsen P level, as OC content increased the amount of fertilizer P required to achieve a yield target decreased. It was shown that OC may be used to approximate the contribution of organic P mineralization to plant available soil P during a growing season. The reliability of fertilizer recommendations based on Olsen P may be improved on some alkaline soils by consideration of soil OC content.
Tài liệu tham khảo
Abbot JL (1978) Importance of the organic fraction in extracts of calcareous soils. Soil Sci Soc Am J 42: 81–85
Adepetu JA and Corey RB (1976) Organic phosphorus as a predictor of plant available phosphorus in soils of Southern Nigeria. Soil Sci 122: 159–164
Bowman RA and Cole CV (1978a) Transformations of organic phosphorus in substrates in soils evaluated by NaHCO3 extraction. Soil Sci 125: 49–54
Bowman RA and Cole CV (1978b) An exploratory method for fractionation of organic phosphorus form grassland soils. Soil Sci 125: 95–101
Brar SPS, Bishnoi SR and Singh B (1987) Effect of soil characteristics on the P supplying capacity of soil. Proc National Symp Macronutrients in soils and crops, 21–23 Dec. 1987, Punjab Agri Univ Ludhiana
Daughtrey ZW, Gillman JW and Kamprath EJ (1973) Soil test parameters for assessing plant available P of acid organic soils. Soil Sci 115: 438–446
Dormaar JF (1972) Seasonal pattern of soil organic phosphorus. Can J Soil Sci. 52: 107–112
Greb BW and Olsen SR (1967) Organic phosphorus in calcareous Colorado soils. Soil Sci Soc Am Proc 31: 85–89
Harrison AF (1987) Soil organic phosphorus. A review of world literature. C.A.B. International, Wallingford, England, 257pp
Lins IDG and Cox FR (1989) Effect of extractant and selected soil properties on predicting the optimum phosphorus fertilizer rate for growing soybeans under field conditions. Commun Soil Sci Plant Anal 20: 319–333
Lins IDG, Cox FR and Nicholaides JJ III (1985) Optimizing phosphorus fertilization rates for soybeans grown on Oxisols and associated Entisols. Soil Sci Soc Am J 49: 1457–1460
McLaughlin MJ, Alston AM and Martin JK (1988) Phosphorus cycling in wheat-pasture rotations. III. Organic phosphorus turnover and phosphorus cycling. Aust J Soil Res 26: 343–353
Olsen SR, Cole CV, Watanabe FS and Dean LA (1954) Estimation of available phosphorus in soils by extraction with sodium bicarbonate. USDA Circ No 939
Sharpley AN (1985) Phosphorus cycling in unfertilized and fertilized agricultural soils. Soil Sci Soc Am J 49: 905–911
Uriyo AP and Kesseba A (1975) Amounts and distribution of organic phosphorus in some soils in Tanzania. Geoderma 13: 201–210
Walkley A and Black CA (1934) An examination of the degtjareff method for determining soil organic matter and a proposed modification of the chromic acid titration method. Soil Sci 37: 29–38
White RE (1981) Retention and release of phosphate by soil and soil constituents. In: Tinker PB (ed) Soils and agriculture: critical reports on applied chemistry, Vol. 2, pp 71–114. Halsted Press, NY