Microsoft Word - 24-Agra_13231.doc 203 Original Article Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 PHYSICAL INDICATORS OF SOIL QUALITY OF ALFISOL UNDER CONVENTIONAL SYSTEM OF PHYSIC NUT INDICADORES FÍSICOS DA HQUALIDADE DE ARGISSOLO SOB PLANTIO CONVENCIONAL DE PINHÃO MANSO Cláudia Liane Rodrigues de LIMA 1 ; Clenio Nailto PILLON 2 ; Sérgio Delmar dos Anjos e SILVA 2 ; Roberta Jeske KUNDE 1 1. Professora, Doutora, Universidade Federal de Pelotas, Faculdade de Agronomia Eliseu Maciel, Departamento de Solos, Pelotas, RS, Brasil. clrlima@yahoo.com.br; 2. Pesquisador da Embrapa Clima Temperado, Pelotas, RS, Brasil; 3. Bacharel em Química Ambiental, Mestranda em Agronomia da Faculdade de Agronomia Eliseu Maciel, Pelotas, RS, Brasil. ABSTRACT: The implantation and development of alternative crops to production of biofuel are dependents of soil structural quality. The physic nut has been considered as one of the promising sources of biofuel. The objective of this study was to quantify the influence of use systems on some indicators of soil physical quality and to identify critical values of bulk density and air-filled porosity to crop development of an Alfisol under conventional system of physic nut. For the evaluation of physical indicators of soil quality, samples were collected with disturbed and indisturbed structure in different sampling positions (crop row and interrow). The samples were taken of the layers 0.00 - 0.05; 0.05 - 0.10 and 0.10 - 0.20 m depth. In the conditions of this study, concluded that: i) except to 0.10 to 0.20 m depth, the sampling positions influenced all soil physical parameters; ii) the crop row position presented higher macroporosity and total porosity in 0.00 to 0.10 m depth; iii) the critical air-filled porosity and bulk density values for plant growth were 0.74 and 1.49 Mg m-3 and iv) considering the bulk density and air-filled porosity only the crop row position no indicate restrictive values to plants development. KEYWORDS: Jatropha curcas. Porosity. Aeration. Aggregation. INTRODUCTION The understanding and quantification of the impact caused by soil use and management system on the soil physical quality are fundamental for the development of sustainable agriculture. The agricultural potential of crops as physic nut may be altered by a number of stress factors that are encountered by roots in their environment. Recently, researchers have demonstrated the effects of soil fertility (MARTINS et al., 2010) and accumulated of chemical elements in the leaves and fruits of physic nut (LAVIOLA; DIAS, 2008). Studies registered the influence of different levels of wastewater and doses of phosphorus on the productivity and oil content of physic nut seeds (SOUSA et al., 2011). The management system adopted affects the plant growth and agricultural productivity. It is believed that compaction of the agricultural areas affects the physical, chemical and biological properties of soils and has been considered as one of the main causes of agricultural degradation. The limitation of agricultural production to be depende on soil physical parameter as bulk density, mechanical impedance to root growth and air-filled porosity (LHOTSKÝ et al., 1991; FLOWERS; LAL, 1998). The satured hydraulic conductivity also is one important parameter of soil physical quality (DUNGAN et al., 2007). The compaction depends on the internal and external factors. The external factors have been the intensity and frequency of heavy machines and stress animal trampling. The internal factors has been the soil texture and soil water content (ASSOULINE et al., 1997; DEFOSSEZ; RICHARD, 2002). The continuous increases in the weight of farm machinery and the necessity to use heavy machines in unfavorable soil condition have increased the potential of damage (ALAKUKKU et al., 2003; ALAOUI; DISERENS 2011) and consequently the root growth of crops suffered some degree of restriction. However, a favorable environment to plant growth may be obtained by reducing the soil stress factors. Studies have showed the effect significant of management systems on indicators of soil quality in the crop row and interrow on orchards. Timlin et al. (2001) compared the soil water content dynamics in row and interrow positions in a soybean crop under conventional (plow) tillage. Logsdon et al. (2010) evaluated the effect of corn or soybean row position on soil water. The effects of tillage and intra-row compaction on seedbed properties and red lentil emergence under dry land conditions have been tested (ALTIKAT; CELIK, 2011). Received: 29/06/11 Accepted: 05/11/11 204 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 The bulk density has been extensively used to compare tillage effects on soil structure. Sanches et al. (1999) evaluated the effects of tillage (no-till and conventional tillage) and position relative to the crop (row and interrow) on bulk density and identify whether bulk density variation relative to the crop position is systematic. The authors indicated that bulk density was higher in the interrow position. Lima et al. (2004) reported that soil parameters was influenced by the traffic intensity on orchard, since that the compaction was different between the sampling positions (canopy projection, interrow and row). Recently, little is known about soil management may affect physic nut growth. The critical or restrictive values have not been tested. The knowledge of the critical values would help decision about soil management and consequentely, improvements in soil quality for crop growth and yield. It is necessary to increase the studies in these areas to evaluated critical values for crop development. Despite the benefits of tillage for physic nut establishment and production, in the present study we tested the hypothesis that soil physical attributes could be altered by sampling positions (crop row and interrow) on orchards. However, the objective of this study was to quantify the influence of use systems on some indicators of soil physical quality and to identify critical values of bulk density and air-filled porosity to crop development of an Alfisol under conventional system of physic nut. MATERIAL AND METHODS Study area The study was performed in the Embrapa Temperate Climate Research Center, Rio Grande do Sul, state at latitude 31° 41’ 10” S, longitude 52°26’00” W (reference coordinates) and altitude 13 m. The climate of the region was classified according to Köepen’s classification as Cfa. The area, that has been cultivate with physic nut (PN) (Jatropha curcas L.) under Alfisol, with clayed medium texture (B horizon). The soil texture in the 0.20 m (topsoil) is sand loamy (180 g kg-1of silt, 670 g kg-1 of sand e 150 g kg-1 of clay). The study was stablished in two areas and two sampling positions (row, R and interrow, IR). The first one area was established in August, 2006 (PN1R; PN1IR) and the other implanted in October, 2007 (PN2R, PN2IR). The total área of the experiment is 1.024 m2 with absence of crops covering in the crop row position. The crop interrow position presented growth of spontaneous vegetation. The spacing of cultivate rows and crops in the two areas was about of 3 x 2 m, respectively. The management system utilized was conventional tillage of physic nut performed with tractor of 75 CV and with others farms equipments (plow, rotary tiller and offset disk). One adjacent natural area was used as comparation to results obtained. This area has soil, vegetation type, topography and other characteristics representative of the Pampa Biome of south Brazil. Soil measurements In the two areas and two sampling positions (row, R and interrow, IR), the samples were taken on March 2008 in the layers 0.00 – 0.05; 0.05 – 0.10 and 0.10 – 0.20 m depth. A total of ninety (6 field replications x 5 treatments x 3 layers) indisturbed cores (5 cm diameter by 5 cm length) were collected. In this indisturbed samples, the bulk density (BLAKE; HARTGE, 1986), the soil porosity (EMBRAPA, 1997) and the saturated hydraulic conductivity (KθS) (LIBARDI, 2005) were evaluated. Acoording to Mcbride & Joose (1996) was also evaluated the air-filled porosity using the following equation: AFP = 1− Bd Pd , where Pd: soil particle density (2.58 Mg m-3) and Bd: bulk density (Mg m-3). A total of forty five (3 field replications x 5 treatments x 3 layers) disturbed cores were taken of the layers 0.00 – 0.05; 0.05 – 0.10; 0.10 – 0.20 m depth to evaluate the soil particle density (Pd), aggregate stability and mean weigth diameter (YODER, 1936; KEMPER; ROSENAU, 1986; PALMEIRA et al., 1999). The soil macroaggregates (aggregates > 0.25 mm) and soil microaggregates (aggregates < 0.25 mm) were evaluated using method of Tisdall & Oades (1982). Statistical analysis Analyses of variance and least significant difference were used to evaluate the results. Linear regression analysis between bulk density, air-filled porosity and saturated hydraulic conductivity were also established. The statistical analysis was perfomed using P < 0.05 probability level and the SAS software (SAS INSTITUTE, INC., 1991). RESULTS AND DISCUSSION The statistical moments of the parameters obtained are shown in Table 1. The wide range of variability of the physical characteristics principally 205 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 of soil macroporosity (MA) (47%) and Kθs (97%) (Table 1) are associated with the different sampling positions. Similarly, Lima et al. (2006) have indicated one the wide range of MA and Kθs under Alfisol under citrus orchard. Lowest variability was indicated to soil microporosity (7.95%), bulk density (9%) and soil macroaggregates (9.44%) (Table 1). This indicates that these parameters were lowest sensitive to evaluate soil structural quality. The magnitude of bulk density for cultivated soils commonly varies from 0.9 to 1.8 Mg m-3 (ERBACH, 1987). In general, the bulk density of a mineral soil is 1.3 Mg m-3 (SINGH et al., 1992), that corroborate with the average bulk density obtained (Table 1). Table 1. Statistical moments of the soil physical parameters analysed. Parameters1 Mean Standard desviation Minimum Maximum Coefficient of variation, % MA 13.39 6.24 2.94 28.60 46.64 MI 22.16 1.76 18.36 25.59 7.95 PT 35.56 5.25 26.46 47.96 14.76 AFP 0.76 0.11 0.55 0.93 14.69 Bd 1.42 0.13 1.16 1.66 9.00 Kθs 35.95 34.91 0.70 177.23 97.11 MWD 1.61 0.34 0.80 2.20 20.86 Macroag. 68.01 6.42 54.19 82.08 9.44 Microag. 31.99 6.42 17.92 45.81 20.07 1MA = macroporosity (m 3 m-3); MI = microporosity (m 3 m-3); PT: total porosity (m 3 m-3); AFP: air-filled porosity, Bd = bulk density (Mg m-3); Kθs = saturated hydraulic conductivity (mm h -1); MWD = mean weigth diameter (mm); macroag = macroaggregates (%); microag = microaggregates (%). Statistical tests indicated that MA values were associated with total porosity (PT). In the row position and 0.00 - 010 m depth, the Ma and PT values were highest and statistically similar. In the layer 0.10 – 0.20 m depth and interrow position (PN2IR) was indicated significant decrease of MA probably caused by traffic of vehicle and consequently highest bulk density values in this position (Table 2). The air-filled porosity indicates the air space present in the soil pores (LIBARDI, 2005). The AFP was lower in the interrow and higher in the row position to 0.00 - 0.10 m depth and similar to 0.10 – 0.20 m depth (Table 2). In general, the soil in the interrow position to 0.00 – 0.10 m, was denser, originating smaller water permeabiliy (Kθs) (Table 2) by traffic of vehicles and higher soil compaction. The values of Kθs in the crop interrow were higher than indicated by Jarecki & Lal (2005). Similar statistical values of Kθs (0.10 – 0.20 m) are associated with the variability of results (Table 1). It is in accordance with Silva et al. (2007). The values of these parameters suggest that the interrow position studied has been subject to high loads, principaly to 0.00 – 0.10 m depth. Vehicles with high weight per axis and high air tire inflation pressure indicate low AFP and consequently soil compaction. Silva et al. (2003) postulated that traffic intensity altered the bulk density, soil porosity and saturated hydraulic conductivity. However, in this study, no differences were presented only in the 0.10 - 0.20 m depth (Table 2) In general, the mean weight diameter was influenced by sampling position in all layers studied (Table 2). However, were similar the aggregates size distribution of 2.00 – 1.00 mm and < 0.25 mm. The Figure 1 summarizes that the diameter of aggregates of 2.00 – 1.00 mm was smaller. The mean of macroaggregates and microaggregates values, i.e. aggregates higher and lower than 0.25 mm, respectively are listed in Table 3. The distribuition of soil aggregates indicated about structural quality of soil (Figure 1). Similar results statistically were encountred in both treatments and layers, so this soil parameter demonstrated no sensitive to soil use. However, tillage systems affect soil aggregation, bulk density and seedling emergence (ALTILAK; CELIK, 2011) 206 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 Table 2. Macroporosity (MA, m 3 m-3), microporosity (MI, m 3 m-3), total porosity (PT, m 3 m-3), air-filled porosity (AFP), bulk density (Bd, Mg m-3), saturated hydraulic conductivity (Kθs, mm h -1) and mean weight diameter (MWD, mm) of an Alfisol under different areas and layers. MA MI PT AFP Bd Kθs MWD 0,00 - 0,05 m PN1R 21,74 a 20.40 d 42.13 a 0.98 a 1.24 c 108.79 a 1.70 a PN1IR 10.12 c 23.62 ab 33.74 c 0.74 b 1.48 a 9.18 c 1.76 a PN2R 20.96 a 21.83 c 42.79 a 0.93 a 1.28 bc 60.64 b 1.29 b PN2IR 6.64 d 24.37 a 31.01 d 0.69 b 1.53 a 8.67 c 1.55 ab AN 13.90 b 22.99 bc 36,90 b 0.92 a 1.33 b 60.45 b 1.86 a Pr > F < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 < 0.0001 0.0410 lsd 2.99 1.33 2.71 0.079 0.065 40.45 0.38 0.05 – 0.10 m PN1R 22.37 a 19.52 c 41.88 a 0.94 a 1.27 c 9.28 b 1.89 ab PN1IR 10.37 bc 21.37 b 31.73 bc 0.70 cd 1.52 ab 10.19 ab 2.21 a PN2R 21.12 a 21.69 b 42.81 a 0.88 ab 1.27 c 11.44 a 1.50 b PN2IR 6.44 c 23.53 a 29.98 c 0.66 d 1.56 a 11.21 a 1.85 ab AN 12.79 b 21.26 b 34.05 b 0.80 bc 1.44 b 7.49 c 2.08 a Pr > F < 0.0001 0.0012 < 0.0001 < 0.0002 < 0.0001 < 0.0001 0.0452 lsd 4.08 1.66 3.08 0.1167 0.082 5.77 0.47 0.10 – 0.20 m PN1R 12.74 a 21.66 b 34.39 a 0.75 a 1,48 a 34,24 a 1,76 a PN1IR 11.03 a 21.49 b 32.52 ab 0.75 a 1.48 a 34.25 a 1.46 ab PN2R 12.31 a 23.92 a 36.23 a 0.74 a 1.46 a 11.51 a 1.38 b PN2IR 6.26 b 23.55 a 29.81 b 0.64 a 1.58 a 19.92 a 1.69 a AN 12.21 a 21.21 b 33.42 ab 0.79 a 1.45 a 37.51 a 1.76 a Pr > F 0.0450 0.0002 0.0407 0.0812 0.0837 0.1578 0.0354 lsd 4.62 1.25 4.04 0.1047 0.096 24.29 0.30 PN1R: soil under physic nut with 19 months of implantation (crop row); PN1IR: soil under physic nut with 19 months of implantation (crop interrow); PN2R: soil under physic nut with 5 months of implantation (crop row); PN2IR: soil under physic nut with 5 months of implantation (crop interrow) and AN: natural area. Same letter on the column by soil layer indicates no statistical difference at 5% significance level. Pr: probability; lsd: least significant difference. Table 3. Macroaggregates (macroag.) and microaggregates (microag.) of an Alfisol under different areas and layers. 0.00 – 0.05 m 0.05 – 0.10 m 0.10 – 0.20 m Macroag. Microag. Macroag. Microag. Macroag. Microag. PN1R 69.46 30.54 72.40 27.60 68.14 31.86 PN1ER 66.95 33.05 72.01 27.99 67.61 32.39 PN2R 66.40 33.60 70.07 29.92 68.71 31.29 PN2ER 60.69 39.31 68.12 31.88 67.18 32.82 AN 68.28 31.72 68.67 31.33 65.38 34.62 PN1R: soil under physic nut with 19 months of implantation (crop row); PN1IR: soil under physic nut with 19 months of implantation (crop interrow); PN2R: soil under physic nut with 5 months of implantation (crop row); PN2IR: soil under physic nut with 5 months of implantation (crop interrow) and AN: natural area. 207 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 a) 8,00-4,76 4,76-2,00 2,00-1,00 1,00-0,50 0,50-0,25 <0,25 0 5 10 15 20 25 30 35 40 45 50 E s ta b le a g g re g a te s , % Diameter of aggregates, mm PN 1L PN 1EL PN 2L PN 2EL AN b) 8,00-4,76 4,76-2,00 2,00-1,00 1,00-0,50 0,50-0,25 <0,25 0 5 10 15 20 25 30 35 40 45 50 E s ta b le A g re g g a te s , % Diameter of aggregates, mm PN 1R PN 1IR PN 2R PN 2IR AN c) 8,00-4,76 4,76-2,00 2,00-1,00 1,00-0,50 0,50-0,25 <0,25 0 5 10 15 20 25 30 35 40 45 50 E s ta b le a g g re g a te s , % Diameter of aggregates, mm PN 1R PN 1IR PN 2R PN 2IR AN Figure 1. Water stable aggregates (%) in different diameter of aggregates of an Alfisol and layers: a) 0.00 – 0.05 m, b) 0.05 - 0.10 m and c) 0.10 - 0.20 m. PN1R: soil under physic nut with 19 months of implantation (crop row); PN1IR: soil under physic nut with 19 months of implantation (crop interrow); PN2R: soil under physic nut with 5 months of implantation (crop row); PN2IR: soil under physic nut with 5 months of implantation (crop interrow) and AN: natural area. The vertical bars indicate the least significant difference between soil use and within diameter of soil aggregates. 208 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 The soil quality for crop development has been evaluated with mathematical models of soil parameters (ATKINSON et al., 2007). Considering that advances in stablishing of critical values of soil physical parameters for crop growth and yield have been made (Lima et al., 2010), the regression analysis showed that the bulk density (F= 333.29; P < 0.0001; R2 = 0.82) (Figure 2a) and the air-filled porosity (F= 322.15; P < 0.0001; R2 = 0.82) (Figure 2b) were statistical significant and depends of MA. According to objective of this study and considering 10%, wich critical value of soil porosity for crop development (GRABLE; SIEMER, 1968), observed that critical bulk density value was 1.49 Mg m-3 (Figure 2a). However, yet was observed that AFP > 0.74 is satisfatory for plants development (Figure 2b). The interrow position (PN2IR) was indicated lowest MA value and critical Bd and AFP values (Table 2). This probabily was associated with the intensity of soil use in these areas. The linear regression models associated with Kθs indicated significant dependence of MA (F = 48.46; P < 0.0001; R2 = 0.40) and Bd (F = 42.71; P < 0.0001; R2 = 0.37) values. a) b) Figure 2. Relationship between (a) macroporosity (MA) and bulk density (Bd) and (b) MA and air-filled porosity (AFP) of an Alfisol to 0.00 – 0.20 m depth. Studies have demonstrated that crop productivity is reduced when the critical values of soil bulk density, air-filled porosity, soil macroporosity and hydraulic conductivity (defined when plant development is limited) are exceeded (SILVA; KAY, 1997; REICHERT et al., 2009). However, it is still necessary to develop more studies that allow a better understanding the compaction process of soils developed under orchard of physic nut. CONCLUSIONS The row and interrow positions influenced the soil parameters studied, except 0.10 – 0.20 m depth. In the row position and 0.00 – 0.10 m was 209 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 indicated higher soil macroporosity and total porosity. The critical air- filled porosity and bulk density values for crops development were 0.74 and 1.49 Mg m-3, respectively. The crop row position indicated best results of soil physical properties associated with a lower bulk density and adequate air-filled porosity. RESUMO: A implantação e o desenvolvimento de culturas alternativas para a produção de biocombustível são dependentes da qualidade estrutural do solo. O pinhão manso tem sido considerado uma fonte promissora de biocombustível. O objetivo deste estudo foi verificar a influência dos sistemas de uso em alguns parâmetros físicos e identificar valores críticos ao desenvolvimento de plantas de um Argissolo Vermelho Amarelo sob sistema convencional de pinhão manso. Coletaram-se amostras com estrutura alterada e inalterada, nas posições linha e entrelinha de cultivo do pinhão manso e nas camadas de 0,00 a 0,05; 0,05 a 0,10 e 0,10 a 0,20 m. Nas condições deste estudo, conclui-se que: i) as posições de amostragem influenciam os parâmetros físicos com exceção da camada de 0,10 - 0,20 m; ii) na camada de 0,00 - 0,10 m, o solo na posição linha de cultivo apresentou uma maior macroporosidade e porosidade total do solo; iii) os valores críticos ao desenvolvimento de plantas referentes ao índice de vazios e de densidade do solo são 0,74 e 1,49 Mg m- 3 e v) considerando o índice de vazios e a densidade do solo, somente o solo na posição linha de cultivo não indica valores limitantes ao desenvolvimento da cultura. PALAVRAS-CHAVE: Jatropha curcas. Porosidade. Aeração. Agregação. REFERENCES ALAKUKKU, L.; WEISSKOPF, P.; CHAMEN, W. C. T.; TIJINK, F. G. J.; VAN DER LINDEN, J. P.; PIRES, S.; SOMMER, C.; SPOOR, G. Prevention strategies for field traffic-induced subsoil compaction: a review. Part I. Machine/soil interactions. Soil and Tillage Research, Amsterdan, v. 73, p. 145-160, 2003. ALAOUI, A. DISERENS, E. Changes in soil structure following passage of a tracked heavy machine. Geoderma, Amsterdan, v. 163, p. 283-290, 2011. ALTIKAT, S.; CELIK, A. The effects of tillage and intra-row compaction on seedbed properties and red lentil emergence under dry land conditions. Soil and Tillage Research, Amsterdan, v. 114, p. 1-8, 2011. ASSOULINE, S.; TAVARES FILHO, J.; TESSIER, D. Effects of compaction on soil physical and hydraulic properties: Experimental results modeling. Soil Science Society of America Journal, Madison, v. 61, p. 390- 398, 1997. ATKINSON, B. S.; SPARKES, D. L.; MOONEY, S. J. Using selected soil physical properties of seedbeds to predict crop establishment. Soil and Tillage Research, Amsterdam, v. 97, p. 218-228, 2007. BLAKE, G. R.; HARTGE, K. H. Bulk density. In: KLUTE, A. (Ed.). Methods of soil analysis. Madison: American Society of Agronomy, 1986. p. 377-382. DEFOSSEZ, P.; RICHARD, G. Models of soil compaction due to traffic and their evaluation. Soil and Tillage Research, Amsterdam, v. 67, p. 41-64, 2002. DUNGAN, R. S.; LEE, B. D.; SHOUSE, P.; KOFF, J. P. Saturated hydraulic conductivity of soil blended with waste foundry sands. Journal of Soil Science, London, v. 172, p. 751-758, 2007. EMBRAPA, Empresa Brasileira de Pesquisa Agropecuária. Centro Nacional de Pesquisa de Solos. Manual de métodos de análise de solo. 2. ed. rev. atual. Rio de Janeiro: Embrapa Solos, 1997. 212 p. ERBACH, D. C. Measurement of soil bulk density and moisture. Transactions of the American Society of Agricultural Engineers, Madison, v. 4, p. 922-929, 1987. 210 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 FLOWERS, M. D.; LAL, R. Axle load and tillage effects on soil physical properties and soybean grain yield on a mollic ochraqualf in northwest Ohio. Soil and Tillage Research, Amsterdam, v. 48, p. 21-35, 1998. GRABLE, A. R.; SIEMER, E. G. Effects of bulk density aggregate size and soil water suction on oxygen diffusion, redox potential and elongation of corn roots. Soil Science Society of America Journal, Madison, v. 32, p. 18-186, 1968. JARECKI, M. K.; LAL, R. Soil organic carbon sequestration rates in two long-term no-till experiments in Ohio. Journal of Soil Science, London, v. 70, p. 280-291, 2005. KEMPER, W. D.; ROSENAU, R. C. Aggregate stability and size distribuition. In: Methods of soil analysis. Physical and mineralogical methods. 2. ed., Madison, Wisconsin: American Society of Agronomy, p. 425- 443, 1986. LAVIOLA, B. G.; DIAS, L. A.dos S. Teor e acúmulo de nutrientes em folhas e frutos de pinhão manso. Revista Brasileira de Ciência do Solo, Viçosa, v. 32, p. 1969-1975, 2008. LHOTSKÝ, J.; BERAN, P. PARIS, P.; VALIGURSKÁ, L. Degradation of soil by increasing compression. Soil and Tillage Research, Amsterdan, v. 19, p. 287-295, 1991. LIBARDI, P. L. Dinâmica da água no solo. São Paulo: EDUSP, 2005. 335p. LIMA, C. L. R.; SILVA, A. P.; IMHOFF, S.; LIMA, H. V.; LEÃO, T. P. Heterogeneidade da compactação de um Latossolo Vermelho-Amarelo sob pomar de laranja. Revista Brasileira de Ciência do Solo, Viçosa, v. 28, p. 409-414, 2004. LIMA, C. L. R.; REINERT, D. J.; REICHERT, J. M.; SUZUKI, L. E. A. S.; GUBIANI, P. I. Qualidade físico- hídrica e rendimento de soja (Glycine max L.) e feijão (Phaseolus vulgaris L.) de um Argissolo Vermelho distrófico sob diferentes sistemas de manejo. Ciência Rural, Santa Maria, v. 36, p. 1172-1178, 2006. LIMA, C. L. R.; REINERT, D. J.; REICHERT, J. M.; SUZUKI, L. E. A. S. Produtividade de culturas e resistência à penetração de Argissolo Vermelho sob diferentes manejos. Pesquisa Agropecuária Brasileira, Brasília, v. 45, p. 89-98, 2010. LOGSDON, S. D.; SAUER T. J.; HERNANDEZ-RAMIREZ G.; HATFIELD J. L.; KALEITA-FORBES A.; PRUEGER J. H. Effect of Corn or Soybean Row Position on Soil Water. Soil Science Journal, Baltimore, v. 175, p. 530-534, 2010. MARTINS, L. D.; TOMAZ, M. A.; AMARAL, J. F. T. do; LAVIOLA, B. G.; BORCARTE, M. Desenvolvimento inicial de mamona e pinhão manso em solo submetido a diferentes corretivos e doses de fósforo. Revista Verde de Agroecologia e Desenvolvimento Sustentável, Mossoró, v. 5, p. 143 – 150, 2010. MCBRIDE, R. A.; JOOSSE, P. J. Overconsolidation in agricultural soil: Pedotransfer functions for estimating preconsolidation stress. Soil Science Society of America Journal, Madison, v. 60, p. 373-380, 1996. PALMEIRA, P. R. T.; PAULETTO, E. A.; TEIXEIRA, C. F. A.; GOMES, A. S.; SILVA, J. B. Agregação de um Planossolo submetido a diferentes sistemas de cultivo. Revista Brasileira de Ciência do Solo, Campinas, v. 23, p. 189-195, 1999. REICHERT, J. M.; SUZUKI, L. E. A. S.; REINERT, D. J.; HORN, R.; HÄKANSSON, I. Reference bulk density and critical degree-of-compactness for no-till crop production in subtropical highly weathered soils. Soil and Tillage Research, Amsterdan, v. 102, p. 242-254, 2009. 211 Physical indicators... LIMA, C. L. R. et al. Biosci. J., Uberlândia, v. 28, Supplement 1, p. 203-211, Mar. 2012 SANCHES, A. C.; SILVA, A. P.; TORMENA, C. A.; RIGOLIM, A. T. Impacto do cultivo de citrus em propriedades químicas, densidade do solo e atividade microbiana de um Podzólico Vermelho-Amarelo. Revista Brasileira de Ciência do Solo, Viçosa, v. 23, p. 91-99, 1999. SAS, INSTITUTE. SAS/STAT procedure guide for personal computers. 5 ed. Cary: SAS Institute, 1991, 1104p. SILVA, A. P. da; KAY, B. D. Estimating the least limiting water range of soil from properties and management. Soil Science Society of America Journal, Madison, v. 61, p. 877-883, 1997. SILVA, A. L.; REICHARDT, K.; ROVERATTI, R.; BACCHI, O. O. S.; TIMM, L. C.; OLIVEIRA, J. C. M.; DOURADO-NETO, D. On the use of soil hydraulic conductivity functions in the field. Soil and Tillage Research, Amsterdam, v. 93, p. 162-170, 2007. SILVA, R. B.; DIAS JUNIOR, M. S.; SILVA, F. A. M.; FOLE, S. M. O tráfego de máquinas agrícolas e as propriedades físicas, hídricas e mecânicas de um Latossolo dos Cerrados. Revista Brasileira de Ciência do Solo, Viçosa, v. 27, p. 973-983, 2003. SINGH, K. K.; COLVIN, T. S.; ERBACH, D. C.; MUGHAL, A. Q. Tilth índex: an approach to quantifying soil tilth. Transactions of the American Society of Agricultural Engineers, Madison, v. 35, p. 1775-1785, 1992. SOUSA, A. E. C.; GHEYI, H. J.; SOARES, F. A. L.; MEDEIROS, E. P.; NASCIMENTO, E. C. S. Teor de óleo no pinhão manso em função de lâminas de água residuária. Pesquisa Agropecuária Brasileira, Brasília, v. 46, p. 108-11, 2011. TIMLIN, D.; PACHEPSKY, Y.; REDDY, V. R. Soil water dynamics in row and interrow positions in soybean (Glycine max L.). Plant and Soil, Netherlands, v. 237, p. 25-35, 2001. TISDALL, J. M., OADES, J. M. Organic matter and water stable aggregates in soils. Journal of Soil Science, London, v. 33, p. 141-163, 1982. YODER, R. E. A direct method of aggregate analysis of soils and a study of the physical nature of erosion losses. Journal of the American Society of Agronomy, Madison, v. 28, p. 337-351, 1936.