Agronomy EFFECT OF SUBSOLNG ON SOL COMPACTON AND YELD OF SUGARCANE1 Ray Ricaud Agronomy Department, Louisiana Agricultural Experiment Station, Baton Rouge, Louisiana, USA ABSTRACT Soil compaction is becoming a serious problem on sandy soils in the Louisiana sugarcane area. This is due mainly to the use of heavier field equipment under wet conditions and to the lack of effective subsoiling. Several experiments were conducted to determine the effect of subsoiling with a regular subsoiler and a vertical mulcher subsoiler on soil compaction and the yield of sugarcane. The subsoilers were operated under each row to a depth of 61 cm prior to planting in the fall. Subsoiling with a regular subsoiler increased cane yield an average of 11.2 tonslha or 19.3%. Subsoiling with a vertical mulcher subsoiler increased cane yield an average of 21.7 tonslha or 39.9%. This was due to an increase of 19.8% in stalk number and 23.2% in individual stalk weight. The mulcher subsoiler'was considerably more effective than the regular subsoiler in increasing cane yield. The increases were larger in plant cane than in stubble cane. The incorporation of bagasse in the subsoil with the vertical mulcher subsoiler did not increase cane yield. Although large increases in yield were obtained in a second cycle of cane after subsoiling, it was beneficial to subsoil prior to planting each cane crop. NTRODUCTON Soil compaction is becoming a serious problem in sugarcane production in Louisiana. This is due to the increase in the use of heavier field equipment and to the lack of effective deep tillage or subsoiling to reduce soil compaction. The amount of compaction in the soil may vary among soil types depending' mainly on their clay and organic matter content. Most soils can be compacted with heavy equipment traffic under certain moisture conditions.,however, the residual compaction is relatively low in soils with a high clay content due to the shrinking and cracking of the soil during dry periods. Sandy soils with a low clay and organic matter content compact to form a dense layer or hardpan in the subsoil. This hardpan is usually from This research is supported in part by grant funds from the American Sugar Cane League and by sugarcane growers.
1040 AGRONOMY 15 to 20 cm in thickness and occurs immediately below the plowed layer in the soil. t can form by traffic from normal tillage and restrict root development. According to Meredith and Patrick2 soil compaction increases the bulk density 2nd decreases the porosity, water infiltration and root penetration in the soil. The effect of soil compaction on sugarcane yield may depend on the variety of cane and the amount and distribution of rainfall during the growing season. The yield from vigorous varieties with a strong root system is less likely to be adversely affected by soil compaction. However, a poor root penetration in the subsoil can reduce the water uptake and yield of most cane varieties during dry periods in the summer time. Saveson, et a1.4 found that deep tillage can increase cane yield on fine sandy loam and silty clay loam soils, especially in years of poor rainfall distribution. Patrick, et a1.3 reported that deep tillage can increase root development and yield on soils with traffic pans in years of low rainfall. Heilman, et al.1 obtained significant increases in cotton yield from trenching 12.7 dm wide to a depth of 102 cm under each row prior to planting in the low rainfall area of the Rio Grande Valley. The purpose of this paper is to discuss the results from several experiments on subsoiling in the sugarcane area of Louisiana. EXPERMENTAL PROCEDURES Seven experiments were corlducted to determine the effects of subsoiling on the yield and certain growth characteristics of sugarcane. The experiments were on locations; soil types, and with cane varieties shown in Table. TABLE 1. The location, soil type, cane variety and year of each experiment. Experiment Location' Soil Cane number type variety Year conducted 1 Allendale Commerce sil CP48-103 2 Allendale Commerce sil L60-25 3 Allendale Commerce sil L60-25 4 Allendale Commerce sil L62-96 5 Alma Commerce sil CP48-103 6 Patout Jeanerette sil NCO 310 7 Allendale Commerce sil L6Q-25 Sugarcane plantations.
The experiments were located on soil types which appeared to have a compaction problem. Experiments 1, 2, 3 and 4 were with plant and stubble cane on Commerce silt loam soil at different locations on Allendale Plantation in West Baton Rouge Parish. Experiment 5 was with plant and stubble cane on Commerce silt loam soil at Alma Plantation in Pointe Coupee Parish. Experiment 6 was with plant cane on Jeanerette silt loam soil at M. A. Patout Plantation in beria Parish. Experiments 1 through 6 were conducted during the first cycle of cane after subsoiling. Experiment 7 was conducted on Commerce silt loam soil at Allendale to determine the residual effect of subsoiling in a second cycle of cane. The subsoilers tested were a regular su$?oiler and a vertical mulcher subsoiler. The regular subsoiler consisted of la, typical subsoiling shank. t opened a narrow furrow approximately 3.8" cm in width. The vertical mulcher subsoiler was constructed to open a furrow 28 cm wide, at the top and 13 dm wide at the bottom of the subsoiling furrow. t was oqginally designed with a large hopper to incorporate plant residue into the subsoil. The incorporation of bagasse was found to be very difficult and not beneficial for increasing the effectiveness of subsoiling. Therefore, the original model was redesigned and built without the capability for incorporation but retained its original name. The regular subsoiler was tested in Experiments 1 and 2 and the vertical mulcher subsoiler was tested in all the experiments. The incorporation of bagasse was tested in Experiment 1 by filling the subsoiling furrow with bagasse. Experiment 7 was conducted during a second cycle of cane following the first cycle in Experiment 3. The rows were maintained in their original position during the fallow year between cycles to keep the subsoiling furrow under each row. One-half of the subsoiled plots was subsoiled again with a vertical mulcher subsoiler prior to planting the second cycle of cane. The regular and vertical mulcher subsoilers were operated under each row at a depth of 61 cm prior to planting cane on plots in a normal manner after the rows were rebuilt and allowed to settle by rainfall. The plots were three rows wide and from 152 to 244 meters long. The subsoiling treatments, including a check without subsoiling, were replicated three times in a randomized block design in each experiment. The The cane yield and percent brix and sucrose in the cane juice were measured on each plot at a normal harvest time. The sugar yields were calculated in accordance with the data published annually by the U. S. Department of Agriculture on sugar commercially recoverable from sugarcanes. stalk population and the individual stalk weight of the millable cane were measured at harvest time in some of the exhe5iqents. The amount <
1042 AGRONOMY rable 11. Effect of subsoiling on the yield of sugarcane in four experiments on Commerce silt loam soil at Allendale Plantation. Cane Stalk Normal Sugar yield sucrose yield Subsoiling (tons/ha) Number Weight % (Kg/ha) treatment (1000/ha) (Kg/stalk) Exp. 1, plant cane, GP48-103, 1968 53.5 58.8 0.91 16.1 6283 Regular 65.2 66.5 0.98 15.6 7442 V, mulcher 93.7 68.9 1.36 14.7 9925 + bag.' 84.7 69.4 1.22 14.7 9017 15.0 1662 Exp. 1, first stubble, CP48-103, 1969 50.2 70.7 0.71 13.5 48 14 Regular. 60.3 79.3 0.76 14.4 6178 86.7 81.O 1.07 15.7 9986 14.1 1487 Exp. 2, plant cane, L60-25, 1969 78.9 86.7 0.91 13.3 8050 Regular 88.1 82.3 1.07 14.0 9786 107.6 88.9 1.21 13.8 11,690 6.5 619 Exp. 2, first stubble, L60-25, 1970 Regular V, mulcher LSD $05 LSD -0.5 Exp. 3, plant cane, L60-25, 1970 73.6 0.83 15.3 89.2 0.99 14.8 Exp. 3, first stubble, L60-25, 1971 - - 13.1 - - 13.4 - - Exp. 3, second stubble, L60-25, 1971 80.3 0.65 14.3 99.1 0.64 13.9 Exp. 4, plant cane, L-62-96, 1972 54.6 1.01 14.2 70.7 1.19 13.1 Exp. 4, fitst stubble, L62-96, 1973 54.6 0.93 12.9 67.0 1.10 13.0 Exp. 4, second stubble, L62-96, 1974 46.8 60.8 0.77 13.9 4612 59.8 72.9 0.82 14.3 6131 9.0 900 Exp. 4, third stubble, L62-96, 1975 45.7 50.2 0.91 14.1 4610 V, mulcher 67.3 66.0 1.02 13.9 6614 13.9 1392 Bagasse incorporated in subsoil with a vertical mulcher subsoiler.
and distribution of cane roots were observed with and without subsoiling. A soil penetrometer equiped with a probe 1.27 cin in diameter was used to measure soil compaction. RESULTS AND DSCUSSON The data obtained in Experiments 1 through 4 on Commerce silt loam soil at Allendale Plantation are reported in Table 11. The increases in cane and sugar yields with the vertical mulcher subsoiler over the check without subsoiling were relatively large with plant and stubble cane in each experiment. n the two experiments or four crop years in which the regular subsoiler was tested, it produced significant increase in yield only with plant cane in one year. The vertical mulcher subsoiler produced a significant increase in yield over the regular subsoiler in three out of the four crop years. The incorporation of bagasse into the subsoil with the vertical mulcher subsoiler did not increase yield over subsoiling alone. The data obtained in Experiment 5 on Commerce soil at Alma Plantation and in Experiment 6 on a Jeanerette soil at M. A. Patout Plantation are presented in Table 111. The increases in the cane and sugar yields from subsoiling with the vertical mulcher subsoiler were significant at these two locations. However, the increases were smaller on the Jeanerette soil than on the Commerce soil. TABLE. Effect of subsoiling on the yield of sugarcane in Experiment 5 on Commerce soil at Alma Plantation and in Experiment 6 on Jeanerette soil at M.A. Patout Plantation. Cane Normal juice Sugar Subsoiling yield yield treatment (tons/ha) Brix Sucrose Purity (Kg/ha)... %... Exp. 5, plant cane, CP48-103, 1972 54.6 16.9 12.7 75.5 4864 71.7 16.6 12.4 75.0 6192 6.5 544 Exp. 5, second stubble, CP48-103, 1974 V, mulcher Exp. 6, plant cane NC0310, 1974 54.2 16.8 13.0 77.5 4939 60.7 17.6 14.1 80.4 6122,"3 4.9 f s 474.'+" A (<;' -y 1
AGRONOMY A summary of the increases in cane yield, stalk population and weight from subsoiling in the six experiments with first cycle cane is presented in Table V. The regular subsoiler increased cane yields averaging 11.2 tons/ha or 19.3% in two experiments. The increases in cane yields with the vertical mulcher subsoiler in all the experiments or 14 crop years ranged from 6.5 to 40.2 tons/ha with an average of 21.7 tons or 39.9%. The increases were generally largest with plant cane and decreased with each successive stubble crop. TABLE V. ncreases in cane yield, stalk population and individual stalk weight from subsoiling with a regular subsoiler and a vertical mulcher subsoiler. ncreases from subsoilingl Exper. Age of Cane yield Stalk no. Stalk wt. number cane - (tons/ha) % % % Regular subsoiler 1 11.7 21.9 13.1 7.7 1 First stubble 10.1 20.1 12.2 7.0 2 9.2 11.7-5.1 17.6 2 First stubble 13.8 23.7 8.1 14.5 Mean First stubble First stubble First stubble Second stubble First stubble Second stubble Third stubble Second stubble Vertical mulcher subsoiler Mean 21.7 39.9 19.8 23.2 ncreases over the check without subsoiling. The average increases in stalk number and eight were 7.1 and 11.7% respectively with the regular subsoiler and 19.8 and 23.2%, respectively with the vertical mulcher subsoiler. The vertical mulcher subsoiler was considerably more effective than the regular subsoiler in increasing the cane yield, 'millable stalk population and individual stalk weight. The effect of subsoiling with both subsoilers
R. RCAUD was more pronounced in the stalk weight or cane height than in the stalk population. TABLE V. Effect of subsoiling on the yield of sugarcane in a second cycle, of cane in Experiment 7 on Commerce soil at Allendale Plantation1. Stalk Subsoiling Cane Normal Sugar treatment yield (tons/ha) Number (1000/ha) Weight (Kg/stalk) sucrose % yield (Kg/ha) Che'ck Subsoiled first cycle, plant cane, 1974 46.0 65.7 0.70 13.6 4428 Subsoiled first and second cycles, plant cane, 1974 43.1 62.5 0.69 13.8 4238 64.9 77.3 0.84 14.0 6488 7.6 734 Subsoiled, first cycle, first stubble, 1975 38.7 70.4 0.55 14.5 4107 59.1 88.2 0.67 14.1 5926 6.7 689 Subsoiled first and second cycles, first stubble, 1975 37.1 67.4 0.55 14.1 3732 64.4 89.4 0.72 14.3 6617 6.7 689 Subsoiled first cycle, second stubble, 1976 40.7 68.9 0.59 13.5 3901 55.6 85.5 0.65 13.5 5342 4.5 450 Subsoiled first and second cycles, second stubble, 1976 37.2 70.1 0.53 14.0 3719 58.8 87.8 0.67 13.8 5755 4.5 450 ' Plant, first and second stubble yields with variety L60-25 during a second cycle of cane on plots subsoiled with a vertical rnulcher subsoiler prior to the first cycle only and prior to the first and second cycles. The results from subsoiling with a vertical mulcher subsoiler during a second cycle of cane in Experiment 7 are presented in Table V. The yield increases with plant cane were 15.0 tons/ha on plots subsoiled only prior to the first cycle and 21.8 tonsjha on plots subsoiled prior to the first and secind cycles. The yield increases with first stubble cane were 20.4 tonsjha on plots subsoiled prior to the First cycle and 27.3 tons/ha on plots subsoiled prior to the first and second cycles. The yield increases
1046 AGRONOMY with second stubble cane were 14.9 tons/ha on plots subsoiled prior to the first cycle and 21.6 tons/ha on plots subsoiled prior to the first and second cycles. The results indicated that although large increases in yield were obtained in the second cycle after subsoiling, it was beneficialc to subsoil prior to planting each cycle of cane. Also, it was difficult to maintain rows in their original position in order to keep the subsoiling furrow under each row during the fallow year between cane cycles. The effect of subsoiling with a vertical mulcher subsoiler on soil compaction is shown in Table V. The data were obtained during the spring of the first stubble year in Experiment 3 approximately 18 months after subsoiling. TABLE Vi. Effect of subsoiling with a vertical mulcher subsoiler on soil compaction in the first stubble year of Experiment 3 on Commerce soil at Allendale Plantation. Distance from center of row' n hardpan Penetrometer valuesz Below (cm) Not subsoiled Subsoiled hardpan... (Kg)... Penetrometer measurements were made 15.2 cm apart from the center of cane rows to the middles approximately 18 months after subsoiling. Weight required to penetrate the soil with a probe 1.27 cm in diameter. The amount of compaction, as indicated by soil penetrometer values, was very high in the hardpan without subsoiling. The compaction in the hardpan was higher under'the row than under the middles or' inter-row. This was probably due to the deepening of the middles during cultivation. The soil compaction was low under the row after subsoiling. The compaction was lowest in the area of the subsoiling furrow and increased progressively towards the middles. This indicates that the horizontal force caused by the wide subsoiler probably fractured the hardpan on both sides of the subsoiling furrow. However, the compaction was not reduced appreciably in the middles where it was needed for good traction of equipment during harvest time. The penetrometer values were very small below the hardpan indicating no compaction problems deeper in the root zone. The penetration of cane roots through the hardpan on the check plots was very poor. t was estimated by observation that approximately 5% of the roots were feeding below the hardpan without subsoiling. The root
system was considerably deeper where the hardpan was eliminated by subsoiling. The cane leaves showed less symptoms of moisture stress with than without subsoiling during dry periods in the summer time. CONCLUSONS Soil compaction can reduce sugarcane yields on sandy soils, especially during years of low rainfall. A vertical mulcher subsoiler was considerably more effective than a regular subsoiler in reducing soil compaction and increasing cane yield on soils with a conlpacted subsoil. The yield increases from subsoiling with a vertical mulcher subsoiler under each row prior to planting were relatively large with plant and stubble cane. However, the increases were generally larger with plant cane than with the successive stubble crops. The incorporation of bagasse in the subsoil with a vertical mulcher subsoiler was difficult and did not increase yield over subsoiling alone. Although large increases in yield were obtained in a second cycle of cane after subsoiling, it was beneficial to subsoil prior to planting each cane crop. REFERENCES 1. Heilman, M.D. and C.L. Gonzalez. (1973). Effects of narrow trenching in Harlington clay soil on plant growth, rooting depth and salinity. Agro. Jour. 65916-819. 2. Meredith, H.L. and W.H. Patrick, Jr. (1961). Effects of soil compaction on subsoil root penetration and physical properties of three soils in Louisiana. Agro. Jour. 53~163-167. 3. Patrick, W.H., Jr., L.W. Sloane and S.A. Phillips. (1959). Response of cotton and corn to deep placement of fertilizer and deep tillage. Soil Sci. Soc. of Amer. Proceedings. 23:307-310. 4. Saveson,.L., Z.F. Lund and L.G. Davidson. (1966). Deep tillage investigations on alluvial soil in the sugarcane area of Louisiana. 41-123, ARS, USDA. 5. U.S. Department of Agriculture, ASCS. (1968-75). Sugar commercially recoverable- Mainland cane sugar crop. Handbook 3-SU, part 833. EFECTO DEL SUBSOLADO EN LA COMPACTACON DEL SUELO Y EN EL RENDMENTO DE CMA R. Ricaud RESUMEN La compactaci6n constituye un serio problema en 10s suelos arenosos del area caaera de Louisiana. Esto se debe mayormente al uso de equipo pesado que se usa cuando existen condiciones de mucha humedad en 10s suelos y a la falta de la conocida practica de subsolar. Se efectuaron varios *experimentos en 10s que se determino el efecto del subsolado usando,!el subsolador corriente y el, 8., :/ ;,,s t
1048 AGRONOMY "vertical mulcher" en la compactacion del suelo y en el rendimiento de la catia de azlicar. Se trabajo con estos subsoladores a una profundidad de 61 cm antes de la siembra de ototio. Cuando se hizo el subsolado regular, se consiguieron aumentos de 11.2 toneladas por hectarea, o un 19.3 porciento. Cliando se us6 el "vertical mulcher" el aumento en la produccion de caaa fu6 de 21.7 toneladas por hectarea, o un 39.9 porciento. Esto,se debio a un aumento de un 19.8 porciento en el nlimero de caaas y de un 23.2 porciento en el'peso individual de catia. El subsolador del "vertical mulcher" fue mas efectivo que el subsolador regulador. Los aumentos en la produccion fueron mayores en la plantilla que en el retotio. No se registro efecto alguno en la produccion de caaa cuando se incorporo bagaso en el subsuelo con el "vertical mulcher". A pesar de que se obtuvieron buenos aumentos en un segundo ciclo de siembra despues de subsolar, se encontrb que era mas beneficioso subsolar antes de cada