&rq. Fertilization, Soils and Cultural Practices

Transcription

1 Fertilization, Soils and Cultural Practices RELATIONSHIP BETWEEN FERTILIZER AND LEAF BLADE P AND S AND SUGARCANE YIELD IN LOUISIANA Laron E. Golden Louisiana Agricultural Experiment Station Baton Rouge, Louisiana ABSTRACT Fertilizer experiments were conducted in the field to determine the effect of fertilizer P and S on yield and on content of P and S in the leaf blade. Phosphorus, as treble superphosphate, was applied at rates of 0 and 17.4 Ib/ acre. Sulphur, as gypsum, was applied at rates of 0 and 24 Ib/acre. In one experiment in which no S and S treatments were compared, significant increases in yields of cane and sugar/acre were obtained from the fertilizer S. In a combined analysis of 2 X 2 factorial experiments, a significant P X S interaction effect on sugar yield was obtained. The effect arose from a tendency for response to P to be greater when S was applied and, conversely, for response to S to be greater when P was applied. The effect of fertilizer P on leaf blade P content generally was positive, but was not as great as the positive effect of fertilizer S on leaf blade S content. The effect of fertilizer P on leaf blade S content was inconsistent, and the effect of fertilizer S on leaf blade P content generally was negative. Statistically significant correlations were obtained between total P in soils and leaf blade P content, between P extractable from soils and leaf blade P content, and between soil S and leaf blade S content. INTRODUCTION Prior to 1966 normal superphosphate was the source of P in most fertilizer experiments conducted with sugarcane by the Louisiana Agricultural Experiment Station. Significant and economically important increases in sugarcane yields, due to applications of normal superphosphate fertilizer, have been reported at several locations throughout the sugarcane production area of Louisiana (4,7,8,9,10,16,17,18). The increases were generally greater from ratoon cane than from plant cane. With ratoon cane the increases have been as high as 4.48 tons/ acre (7). Additionally, significant correlations of soil test results for extractable P and yield response due to normal superphosphate have been reported in Louisiana (4,7,8). In the finer textured soils of the Recent Mississippi alluvium where correlations were low, physical properties of the soils possibly exert a relatively greater influence on yield responses than do chemical properties. Correlations of soil test results for extractable S and yield response resulting from use of normal superphosphate were not statistically significant (7). &rq Based on analysis of leaf blade samples of sugarcane from several variety - and fertilizer experiments conducted in Louisiana duriqq.,: e 4 year period be- C

2 696 FERTILIZATION, ETC. ginning in 1959 (ll), standard leaf blade values for P were proposed as shown below. Nutritional status of the crop at 3 months of age P content Very low 0.14 Low Medium High Very high 0.26 Sulphur deficiency in sugarcane has been reported from Rhodesia (12), Australia (20), Puerto Rico (3) and India (6). Bonnet (3) reported S applied in fertilizers to be responsible for significant yield increases by sugarcane in Puerto Rico. He concluded that values that approached 0.201, in the sheath of sugarcane variety PR 980 at 7 months of age indicated S deficiency. Samuels (19) reported values of 0.14 and S, dry-weight basis, for 3-6 leaf blade and sheath, respectively, from sugarcane grown in a complete nutrient solution. Halias and Figon (13) suggested a tentative critical level of 0.15% S, dry-weight basis, in leaf lamina of sugarcane sampled at standard boom stage. No standard values for S content of leaf blades of sugarcane have been proposed in Louisiana. In recent years Louisiana sugarcane growers have increased the use of fertilizer P in both liquid and solid forms which contain no S or only small amounts of S. The purpose of this study was to determine the effect of P and S in fertilizers applied to sugarcane on yield and on P and S contents of leaf blades and to ascertain whether experiments should be conducted on a wide range of soil types with fertilizer P and S as independent variables. MATERIALS AND METHODS Six fertilizer experiments were conducted with sugarcane in the field during the period Plot size was approximately 0.1 acre. Treatments were arranged in a complete block design with the number of replications varying from 4-7. The experiments were located at selected commercial plantation sites in the sugarcane growing area of Louisiana. In each experiment N was applied at a constant rate, 160 Ib/acre. The N-only treatment was the check or control. The application rates of P and S were 17.4 and 24 lb/acre, respectively. Anhydrous ammonia, the source of N in 3 experiments, was applied with field applicators in the spring 14 in. from the row in 2 bands at a depth of 10 in. Solid fertilizers were applied in the spring by hand 12 in. from the row in 2 bands at a depth of 6 in. In 3 experiments results from N and NS treatments were compared. In 2 of the experiments gypsum was the source of S and ammonium nitrate was the source of N. In 1 experiment ammonium nitrate was the source of N in the check and ammonium nitrate-sulphate ( s) was the source of S. Am-

3 LARON E. GOLDEN 697 monium nitrate was the source of the remainder of the N required to obtain the N rate of 160 Ibjacre in the NS treatment. Three experiments were conducted in which the treatments were N, NP, NS and NPS. Fertilizer N was applied as anhydrous ammonia. The P was applied as treble superphosphate and S was applied as gypsum. A leaf blade sample, composed of 20 leaf blades, was obtained from each treatment plot. Leaf blades were obtained from the 1st leaf below the top visible dewlap when the sugarcane was approximately 3 months old. When necessary, consideration was given to rainfall and sheath moisture (19) by adjusting the time of sampling a few days. Leaf blade values are reported on a dry-weight basis. Soil samples were obtained from the experimental sites in the spring prior to fertilization. Sugarcane and sugar yield data were obtained from all experiments. Analysis of variance and selected correlations were obtained from field and laboratory data. Carbon in soils was determined by the dry combustion method, and organic matter was determined by multiplying percent carbon by Soil ph was determined by use of a Beckman ph meter. Soil samples were digested with hydrofluoric acid for total P determination. Extractable P was obtained by use of a 0.1 N HC N NH,F solution at a soil solution ratio of 1:20. The soil and extractant mixture for P determination was shaken for 20 minutes. Leaf blade samples were digested with concentrated nitric and perchloric acids for total P determination. The amounts of P in solutions, prepared for total and extractable P determinations in soils, and P from leaf blade digests were determined by the chlorostannous-reduced molybdophosphoric Mue color method in hydrochloric acid system. Soil S and S extractable from soils were determined by the method of Bardsley and Lancaster (2). Soil S has been defined by Bardsley and Lancaster as being the combined organic, oxidizable inorganic and soluble S in soils. They considered the difference in Soil S and extractable S to be reserve S. Total S in leaf blade samples was determined by the magnesium nitrate method of the Association of Official Agricultural Chemists (1). RESULTS Results from soil analyses are presented in Table 1. It may be noted in the table that total P varied from ppm, and extractable P varied from ppm. Soil S varied from ppm, and extractable S varied from ppm. S Experiments, The data in Table 2 show the effect of fertilizer S on yield and on P and S contents of sugarcane leaf blades. The yield differences obtained in experiments 1 and 2 were not significant. The yield increases obtained in experiment 3, 1.67 tons of sugarcane and 570 pounds of sugar per acre, were significant. The P and S contents of sugarcane leaf blades in experiments 1, 2 and 3 were influenced consistently by fertilizer S although differences in leaf blade P only approached significance in experiment 1. In each experiment, a highly significant increase in S content of the leaf blades was obtained due to fertilizer

4 Table 1. Selected chemical properties of topsoil samples from experimental sites. Variety and P (PPm) S (PP~) Experiment Soil age class Organic no. type of cane Year matter (%) Total Extractable Soil Extractable ph 1 Mhoon CP 52-68, sil 2nd ratoon 2 Mhoon CP 52-68, ' sic1 1st ratoon. 3 Mhoon CP 52-68, sic1 2nd ratoon 4 Baldwin CP 52-68, sic1 1st ratoon 5 Sharkey NCo 310, c 2nd ratoon 6 Jeanerette NCo 310, sil 1st ratoon - a =! c N 2 0 "2 M.n

5 LARON E. GOLDEN 699 Table 2, Yield and leaf blade data from experiments with fertilizer S. 2, Leaf blade analyses Experiment Fertilizer Sugarcane Sugar no. treatment yield (tons/acre) yield (lblacre) P (%) s (%) -- 1 N "' NS N ' 0.071** NS N 34.41" 6354" 0.225" 0.102"" NS S. The increase in S content was associated with a significant decrease in the P content in experiments 2 and 3. P-S Experiments Results from 3 2x2 factorial experiments are reported in Table 3. A Table 3. Yield and leaf blade data from experiments with fertilizer P and S. Leaf blade analyses Experiment Fertilizer Sugarcane Sugar no. treatment yield (tonslacre) yield (lb/acre) p (%) s (70) 4 N NP NS NPS N ' NP NS NPS N NP NS NPS combined analysis of data from the experiments indicated highly significant differences among experiments in sugarcane yield, in sugar yield, in leaf blade P contents and in leaf blaae S contents. Sugarcane yield. The fertilizer P and S main effects and fertilizer P X S interaction effect on sugarcane yield were not significant in individual experiments. In the combined analysis, however, a significant main effect increase in sugarcane yield was foiind due to fertilizer P and a main effect increase in sugarcane yield due to fertilizer S approached significance. The fertilizer P X S interaction effect on sugarcane yield also approached significance in the combined analysis. Sugar yield. The fertilizer P and S main effects on sugar yield were not significant in individual experiments. There was a significant fertilizer P X S interaction effect on sugar yield in experiment 4. In the combined analysis, sig-

6 700 FERTILIZATION, ETC. nificant fertilizer P and S main effects on sugar yield were obtained and a significant P X S interaction effect was also obtained. The fertilizer P X S interaction effect noted in experiment 4, together with some P X S interaction effect in experiments 5 and 6, reflected a tendency for response to fertilizer P to be greater when fertilizer S was applied and, conversely, for response to fertilizer S to be greater when fertilizer P was applied. The average sugar yield from the NPS treatment in the 3 experiments was 376 lb/acre higher than the average yield from the N treatment. Leaf blade P. The leaf blade P contents generally were increased due to use of fertilizer P and decreased due to use of fertilizer S. The fertilizer P main effect on leaf blade P was highly significant in experiments 4 and 5 and was significant in experiment 6. The fertilizer S main effect on leaf blade P was not significant in experiment 4 but was highly significant in experiments 5 and 6. The fertilizer P X S interaction effect on leaf blade P was significant only in experiment 6. The effect of fertilizer P on leaf blade P was greater when fertilizer S was applied with fertilizer P and the effect of fertilizer S on leaf blade was greater when fertilizer S was applied alone. In the combined analysis, the fertilizer P and S main effects on leaf blade P were highly significant. The fertilizer P X S interaction effect on leaf blade was not significant. Leaf blade S. Analysis of individual experiments revealed that the fertilizer P main effect on leaf blade S contents was highly significant in each experiment; however, the main effect was negative in experiments 4 and 5 and was positive in experiment 6. In experiment 5, a fertilizer P X S interaction effect on leaf blade S was highly significant. The fertilizer P applied alone in Experiment 5 resulted in a lower leaf blade S value, and fertilizer P*applied with fertilizer S resulted in no effect on leaf blade S content. The fertilizer S main effect on leaf.blade S was positive and was highly significant in each experiment. In the combined analysis, a significant fertilizer P X S interaction effect on leaf blade S merely reflected a need to examine fertilizer P and S effects on leaf blade S in individual experiments. Correlations Correlation coefficients for relationships between total P in the soil and leaf blade P from the N-only treatment (r= 0.899) and between P extractable from the soil and leaf blade P from the N-only treatment (r= 0.912) were significant. The relationship between Soil S and leaf blade S from the N-only treatment (r=0.978) was highly significant. The relationship between S extractable from the soil and leaf blade S from the N-only treatment (r=0.560) was not significant. It is recognized that additional experimental data are needed for the various correlations and for any calibration curves which may be developed from leaf blade and soil chemical values and yields. REFERENCES 1. Associati011 of Official Agricultural Chemists Official Methods of Analysis. Washington, D. C. Ed. 9. p Bardsley, C. E., and J. D. Lancaster Determination of reserve sulfur and soluble sulfates in soils. Soil Sci. Soc. Amer. Proc., 24:

7 LARON E. GOLDEX Bonnett, Juan A Sulfur deficiency in the sheath related to sugarcane yield decline in a Puerto Rico soil. Proc. ISSCT, 12: Bymside, D. S., Jr., and M. B. Sturgis, Soil phosphorus and its fractions as related to response of sugarcane to fertilizer phosphorus. La. Agr. Exp. Sta. Bul Drake, F. R., and B. C. Curnow Sulphur in East Gippsland, Australla. Sulphur Institute J., 4 (1) :lo Dutt, A. K Sulphur deficiency in sugarcane. Emp. J. Exp. Agr., 30: Golden, L. E The uptake of fertilizer phosphorus by sugarcane in Louisiana as measured by radioisotope methods. Proc. ISSCT, The relationship of sugarcane yields to phosphorus and sulphur contents of soils in Louisiana. La. Agr. Exp. Sta. Bul , and Ray Ricaud The nitrogen, phosphorus and potassium contents of sugarcane in Louisiana. La. Agr. Exp. Sta. Bul Fertilizers for sugarcane. Report of Projects, Dept. of Agron., La. Agr. Exp. Sta. p Foliar analysis of sugarcane in Louisiana. La. Agr. Exp. Sta. Bul Gosnell, J. M., and A. C. Long A sulphur deficiency in sugarcane. S$ASTA, 43: Halais, P., and C. Figon Nitrogen and sulphur status of cane leaves as influenced by sulphate of ammonia applications. MSIRI Annual Report. p Jones, M. B., P. W. Lawler, and J. E. Ruckmen Differences in annual clover responses to phosphorus and sulphur. Agron. J., 62: Ludecke, T. E Sulphur in New Zealand pasture production. Sulphur Institute J., 6(2): Ricaud, Ray Effects of fertilizers on yield of sugarcane. Report of Projects, Dept. of Agronomy, La. Agr. Exp. Sta. p Effects of fertilizers on yield of sugarcane. Report of Projects, Dept. of Agron., La. Agr. Exp. Sta. p , L. E. Golden, K. N. Clower, and M. B. Sturgis Fertilizers for sugarcane. Report of Projects, Dept. of Agron., La. Agri. Exp. Sta. p Samuels, G Foliar diagnosis for sugarcane. Agr. Research Publ., Rio Piedras, P. R. P , , ~edl: J. M The sulphur nutrition of sugarcane. Proc. QSSCT, 35: I I!