Atributos físicos e químicos de um planossolo sob sistemas de integração lavoura-pecuária-floresta no agreste da Paraíba

Abstract

Improper management practices may compromise the physical and chemical quality of the soil. In this sense, sustainable alternatives should be adopted in order to maximize food production without compromising soil quality. The Crop-Livestock-Forest integration system (iCLF), becomes a sustainable production alternative, as it integrates the animal and plant components in the same area and its main purpose is to make the soil productive without causing negative impacts on the environment. In this sense, the objective of the present study was to evaluate the physical and chemical attributes of a Haplossol under the Crop-Livestock-Forest (iCLF) integration system in Agreste da Paraíba. The experiment was implemented in 2015 in an experimental area (06°57'00''S and 35º32'42''W; 317 m) of the Paraiban Company for Research, Rural Extension and Land Regularization (EMPAER), in the municipality of Alagoinha (PB). The treatments evaluated were: BG- Gliricidia (Gliricidia sepium (Jacq.) Steud.) + Brachiaria decumbens; BS- Savoy (Mimosa caesalpiniifolia) + Brachiaria decumbens; BI- Purple Ipê (Tabebuia impetiginosa) + Brachiaria decumbens; LA- Corn (Zea mays) + Brachiaria decumbens; BD- Brachiaria decumbens, in a randomized block design (RCB), with four replications. Each plot has a size of 38 x 20 m, totaling an area of 760 m2. Soil samples with deformed and undeformed structure were collected at three depths (0.00-0.10; 0.10-0.20 and 0.20-0.30 m) to determine the following variables: 1) Physical : texture, water-dispersed clay, flocculation degree (FD), percentage of wet and dry macro aggregates (MacroU and MacroS), percentage of wet and dry microaggregates, weighted average diameter of wet and dry aggregates (WMDWa and WMDda), aggregate stability index (ASI), structural stability index (EEI), “S” index, soil density (ρ), maximum soil density (ρMAX), relative soil density (ρR), estimated compaction degree (CD), saturated hydraulic conductivity (Kθ), calculated (α) and estimated (αEst) total porosity, macroporosity and microporosity (Ma and Mi), soil aeration capacity (SAC), relative aeration capacity (θRAC), field capacity (θFC), permanent withering point (θPWP), available water (θAW), available water capacity (WAC), relative field capacity (FCr) and ground water retention curve (WRC); 2) Chemical and fertility: pH in water, total organic carbon (TOC), carbon stock (CSTC), carbon compartmentalization index (CCI), carbon stratification (ΔCE), carbon recovery rate (CRR) , phosphorus (P), potassium (K+), sodium (Na+), calcium (Ca+2), magnesium (Mg+2), Ca + Mg, aluminum (Al+3), hydrogen + aluminum (H++ Al+3), soil organic matter (SOM), base sum (BS), cation exchange capacity (CEC) and base saturation index (V%). Variance analysis, Tukey test (p<0.05), Pearson correlation and principal component analysis were performed. There was no statistically significant variation for most physical and chemical variables and fertility between the evaluated treatments; however, the variables (Ma, S, ρ, ρR, Mi and SAC) were within the limit range considered good. There were significant improvements for COT and WMDWa, especially the BI and BD treatments. It was concluded that after four years of implementation, the evaluated integrated Crop-Livestock-Foresty sisystems promoted significant improvements in the attributes microporosity, weighted average diameter of wet and dry aggregates, percentage of dry macro and microaggregates and elevation in the organic matter contents. soil and total organic carbon. The physical-water variables were the most sensitive within the integration systems according to principal component analysis.