Nutritional Disorders of Grain Sorghum

Crop Production/Industries,

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Not AvailableAvailability, fixation, and transformation of added P were studied in a 16-week incubation experiment with a Vertisol amended with farmyard manure in pots with 500 g soil each. P availability, as measured by Olsen P, decreased for up to 8 weeks with various rates of added P, when no manure was applied. In the presence of farmyard manure, P availability decreased during the first 6 weeks and then showed a considerable increase from the 8th week onwards. P fixation increased for up to 8 weeks with the rates of P in the absence of manure. With manure application, P fixation increased only during the first 6 weeks and thereafter decreased continuously. Thus the presence of farmyard manure shortened the period of P fixation and promoted its availability. After 16 weeks of incubation, when manure and fertilizer P were applied together, P was transformed into labile organic (NaHCO3-P), moderately labile organic P (NaOH-P), and calcium-bound inorganic P (HC1-P). When manure was not applied. P accumulated predominantly as labile inorganic (NaHCO3-P), moderately labile inorganic (NaOH-P), and inorganic HC1-R The application of farmyard manure enriched long-term P fertility through NaHCO3-P and NaOH-P and a shortterm P supply as HCI-R All fractions except inorganic NaOH-P showed good relationships with Olsen P low P concentration of this manure, farmers are not encouraged to use it as a sole fertilizer in intensive crop production. The manure has a high value, however, when applied in large quantities and for a considerably long time (Maurya and Ghosh 1972; Goss and Stewart 1979). Studies have shown that the P in farmyard manure is more readily available and persists over time (Abbot and Tuckar 1973). Farmyard manure retains or immobilizes added R subsequently mineralizes it (Ghosal 1975), and makes it available to plants for an extended period of time. In a study on two paddy soils amended with organic manure, Zhang et al. (1994) reported that labile and moderately labile organic P fractions increased in the Ultisol and decreased in the Entisol, This finding was attributed to differences in the organic matter content of the two soils. In the present study, the behaviour of P as influenced by different rates of added R alone or in the presence of farmyard manure, was investigated in a Vertisol.Not Availabl

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Not AvailableA two-year field experiment was conducted to determine external (soil solution) and internal (plant tissue) P requirement of soybean and wheat crops grown in succession on a Typic Haplustert. Adjusted soil solution P concentrations increased significantly the seed yield of soybean and wheat up to a level of 0.1 mg P VI. Similarly, total P uptake by both the crops increased significantly up to 0.13 mg P VI. Relative yields and relative uptake by the test crops were plotted against solution P concentrations and index leaf P. The computed optimum concentrations of P in solution were 0.10 mg P VI for soybean and 0.11 mg P VI for wheat for obtaining 90 per cent of the yield. Similarly, the optimum external P requirements for 90 per cent of the P uptake were 0.12 mg P L−1 for soybean and 0.12–0.13 mg P L−1 for wheat. The optimum concentration of P was 0.25–0.26 per cent in third fully opened trifoliate leaf of soybean and 0.21–0.25 per cent in flag leaf of wheat.Not Availabl

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Not AvailableMalachite green method has been evaluated for estimating minute quantities of phosphorus (P) in water, 0.01M calcium chloride (CaCl2), and Olsen [sodium bicarbonate (NaHCO3)] extracts often soils of varying properties. The precision and accuracy of the malachite green method was better than that of the ascorbic acid method to estimate P in these three extracts. The recovery of added P ranged from 95.3–99.3% in water, 96–100% in 0.01M CaCl2, and 96.7–100% in Olsen extracts. The ascorbic acid method underestimated the amounts of 0.01M CaCl2‐P and its precision was also lower than the malachite green method. It is possible to predict the P concentration in the three extracts equal to malachite green method from the ascorbic acid P values by using regression equations.Not Availabl

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Not AvailableDuring a 3-year experimental period (between 1992 and 1995), residual effects on yields of subsequent crops of phosphorus applied either to soyabean or wheat, and on recoveries of the added P and changes in the available P, were studied in a soyabean–wheat cropping system on a typic haplustert very low in available P at Bhopal, India. Phosphorus was applied at rates of 0–52 kg P ha-1 (five treatments) to soyabean and 0–39 kg P ha-1 (three treatments) to wheat during the first year, and in the subsequent years the residual effects were studied in relation to fresh applications of 39 kg P ha-1 to each crop. The yields of soyabean and wheat were increased significantly by the application of P to each crop. Phosphorus applied to soyabean showed residual effects in two succeeding crops, whereas P applied to wheat showed a residual effect in only one succeeding crop. Phosphorus applied to soyabean was more efficiently utilized by the succeeding crops compared to that applied to wheat in the rotation. The recoveries of added P were greater with smaller rates of added P and greater in the first two residual crops. Olsen P in soil was adequate only in the first year and it fell below the critical limit in the subsequent two cycles of cropping. Cumulative P uptake by crops determined the levels of available P in the soil and soil test values declined with increase in cumulative P uptake over time.Not Availabl

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Not AvailableIn a greenhouse experiment for two seasons three phosphate carriers (single superphosphate, diammonium phosphate and ammonium polyphosphate) were evaluated for direct and residual effects on wheat and rice, respectively and also for the effectiveness of APP to mobilize soil zinc in Vertic Ustochrept. Among the sources, SSP proved superior to DAP and APP in the production of wheat grain. Single superphosphate and APP recorded larger amount of P uptake by wheat grain compared to DAP. Grain and straw yields and P uptake by these components increased significantly up to 50 mg kg−1 soil level. Among the P sources, APP and SSP maintained higher available P in soil than DAP at flowering and harvesting stages of wheat. The residual effect of P on the succeeding rice showed up to 100 mg kg−1 soil irrespective of the sources of P. Zinc applied @ 5 mg P kg−1 soil to wheat also significantly increased the grain and straw yields and P uptake by rice. The interaction effects revealed that 50 mg P kg−1 soil as either SSP or APP gave higher yield of rice compared to DAP. Available P in soil at flowering stage in case of wheat and before sowing in case of rice bore significant positive relationship with respective grain and straw yields and P uptakeNot Availabl

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Not AvailableIn field experiments with soybean-wheat cropping system conducted during 1992–93 and 1993–94 on a Typic Haplustert, soybean seed yield increased significantly with FYM application up to 4 t ha−1 in 1992 and 16 t ha−1 in 1993. Fertilizer P up to 44 kg ha−1 also progressively improved soybean yield in both the years. Conjoint use of 16 t FYM + 44 kg P ha−1 gave the highest soybean yield. The yield of following wheat crop in both the years increased significantly under the treatment in which the previous crop of soybean received FYM up to 16 t ha−1 and of fertilizer P up to 44 kg ha−1. Integrated use of 16 t FYM (to soybean) + 44kg P ha−1 (to both soybean and wheat) produced the maximum wheat grain yield. Phosphorus uptake by soybean and wheat and available P in the post-harvest soil increased significantly with increasing rates of both FYM and fertilizer P. Averaged over two years, apparent phosphorus recovery (APR) by soybean-wheat system from fertilizer-P ranged from 24.9 to 15.1%, the lower APR being at higher P levels. With FYM applied at 4, 8 and 16 t ha−1, crops recovered about 96, 66 and 45% of manure-P (5.5, 11.0 and 22 kg P ha−1), respectively. In combination with FYM, fertilizer P recovery was greater at all P rates as compared to those with no manureNot Availabl

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Not AvailableLow native soil phosphorus (P) availability coupled with poor utilization ef®ciency of added P is a major constraint limiting the productivity of soybean±wheat system on Vertisols in Indian semi-arid tropics. The use of fertilizer P is limited by its high cost, while organic inputs generally cannot provide suf®cient P for optimum crop growth due to their low P concentration. We, therefore, evaluated in a 5-year ®eld experiment (1992±1997) the effects of integrated use of manure and fertilizer P on crop yield sustainability, P utilization and soil P fertility under soybean±wheat system on a Typic Haplustert. The treatments consisted four rates each of manure (applied only to soybean) and fertilizer P (applied to both soybean and wheat) arranged in a split-plot design with four replications. Both soybean and wheat crops responded signi®cantly to the application of manure and fertilizer P. For the same level of P input, the yield increases were greater with manure P than with fertilizer P. Further, integrated use of fertilizer P and manure was better than their sole application in increasing and sustaining the productivity of soybean±wheat system. The P uptake by the crops increased with increasing rates of manure and fertilizer P and was relatively larger in soybean than in wheat. The per cent phosphorus recovery by the crops from fertilizer P decreased with increasing fertilizer P rate, while it was improved in the presence of manure. Though the extent of fertilizer P recovery was more or less similar in both the crops, soybean was more ef®cient than wheat in extracting the soil and manure P. The available P status of the soil showed a signi®cant build-up during successive cropping seasons due to fertilizer P and the increase was strikingly greater when fertilizer P was applied in combination with manure. The integrated use of manure and fertilizer P is a promising strategy to improve soil P fertility status and to obtain higher and sustained productivity of the soybean-wheat cropping system on Vertisols of the semi-arid tropics. # 1999 Elsevier Science B.V. All rights reserved.Not Availabl