Perdas de solo e nutrientes por erosão num Argissolo com resíduos vegetais de cana-de-açúcar

Abstract

RESUMO:O presente trabalho teve como objetivo determinar as perdas de solo, matéria orgânica (MO) e nutrientes (P, K, Ca e Mg) por erosão, em área cultivada com cana-de-açúcar, cuja palhada é mantida sobre a superfície do solo, localizada em Catanduva -SP, sob um Argissolo Vermelho--Amarelo. Em parcelas experimentais, com 0 (CS 0 ), 50 (CS 50 ) e 100% (CS 100 ) de cobertura sobre a superfície do solo, aplicou-se chuva simulada com intensidade de 60 mm h -1 , durante 65 minutos. Análises do sedimento erodido indicaram taxas de enriquecimento da seguinte ordem: 2,7 a 1,9 (MO), 3,8 a 2,7 (P), 1,3 a 1,7 (K), 3,9 a 3,6 (Ca) e 2,9 a 2,6 (Mg) vezes em relação ao solo original para CS 0 e CS 50 , respectivamente. A CS 50 propiciou controle significativo da erosão de 69%, mas não reduziu a concentração de MO e nutrientes no sedimento erodido. A CS 100 foi significativamente eficiente no controle da erosão (89%) e na redução das concentrações de MO (69%), P (88%), K (23%), Ca (74%) e Mg (75%) no sedimento. PALAVRAS-CHAVE:processo erosivo, simulação de chuva, cobertura do solo. SOIL AND NUTRIENTS LOSSES OF AN ALFISOL WITH SUGARCANE CROP RESIDUE ABSTRACT:The objective of this study was to determine the losses of soil, organic matter (OM) and nutrients (P, K, Ca, and Mg) caused by erosion in an area cultivated with sugarcane containing controlled amount of crop residues in soil surface, in Catanduva city, São Paulo State, Brazil. The soil at the experimental site is an Alfisol. Test plots were 0 (CS 0 ), 50 (CS 50 ) and 100% (CS 100 ) of crop residues cover, submitted to simulated rainfall simulated of 60 mm h -1 , during 65 minutes. Analyses of the eroded sediment indicate an enrichment ratio of 2.7 -1.9 (OM), 3.8 -2.7 (P), 1.3 -1.7 (K), 3.9 -3.6 (Ca), and 2.9 -2.6 (Mg) times in relation to the CS 0 and CS 50 , respectively. The CS 50 was more efficient for controlling the erosion processes in 69%, but not for the reduction of the OM and nutrients losses in the eroded sediment. On the other hand, CS 100 was efficient for erosion control of 89% and in the reduction of OM (69%), P (88%), K (23%), Ca (74%) and Mg (75%) in the eroded sediment.

Clay and Phosphorus Losses by Erosion in Oxisol With Sugarcane Residues

“…With the increase of soil coverage, there was a proportional increase in flow resistance evaluated by Manning roughness coefficient (n) reducing the sediment concentration in the runoff (Figure 2), which increased the viscous forces and increased the ones related to gravity, decreasing the Froude number (Figure 3 These results corroborate with those obtained by MARTINS FILHO et al (2009), who developed studies using different conditions of coverage in Argisol cultivated with sugarcane, keeping the straw on the soil surface, and concluded that by using the soil surface coverage, soil losses by erosion were reduced in 87% in relation to the one obtained in the bare soil. In the oxisol of this research, the soil losses were reduced in 99% with SC of 100% in relation to SC of 0%.…”

“…It was used a rain simulator of rotating rods of Swanson type, equipped with VeeJet 80-100 nozzles. The equipment was calibrated and leveled in the ground, as described by MARTINS FILHO et al (2009).…”

“…In this 1 kg of soil can be absorbed 401 to 552 mg of phosphorus (CAMARGO et al, 2015). The enrichments of the eroded sediment by clay and phosphorus are, likely, consequences of a strong selective erosion which preferably carries the particles of smaller diameter and low density, which is common in interrill erosion (MARTINS FILHO et al, 2009) and is related to the enrichment of eroded sediment by thin low density fractions as silt, clay, phosphorus, nitrogen and organic carbon of the soil (HU et al, 2013).Thus, the sediment enrichment by phosphorus can be attributed to the phosphorus association with the finer soil fractions, which are preferably dragged (KUHN et al, 2010).…”

“…The enrichment ratios (ER) in Figures 7a and 7b are the relation between the concentration of soluble P and adsorbed P in the eroded sediment and the original soil (Table 1).When ER is greater than 1 that means the segment is enriched with organic matter and soil nutrients (MARTINS FILHO et al, 2009, the enrichment rates greater than 1 indicate selectivity of the material dragging in the interrill erosion, which mainly carries the finer particles, the most reactive fractions of the soil and, consequently, with higher capacity of carrying organic carbon and nutrients.…”

INFLUENCE OF LAND USE CHANGE ON SEDIMENT YIELD: A CASE STUDY OF THE SUB-MIDDLE OF THE SÃO Francisco River Basin

“…Within this subject, MARTINS FILHO et al (2009) asserted that the vegetation plays an important role in controlling erosion and reducing the loss of organic matter and nutrients through sedimentation.…”