Uso de Métodos Espectroscópicos para Avaliar o Seqüestro de Carbono em Área de Rotação de Culturas Cana-de-açúcar/Amendoim Sob Diferentes Sistemas de Plantio.

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Proposta de Boas Práticas Agrícolas para as áreas de afloramento do Aqüífero Guarani em Ribeirão Preto, SP.

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Nutrient content in aboveground biomass of Brazilian peanut cultivars in conservation tillage on sugarcane straw and pasture area.

Fields studies were conducted in 2004/2005 in order to evaluate the effects of tillage on nutrient content in aboveground biomass of two peanut cultivars, cultivated in rotation after mechanical harvested sugarcane and pastures. These trials were carried out in two types of soils; Oxisol and Ultisol, respectively in Ribeir?ao Preto and Mirassol, S?ao Paulo State, Brazil. The experimental design was split-plot with four replications. Tillage treatments (conventional, minimum and no-tillage) were main plots while sub-plots were peanut genotypes IAC-Tatu ST (Valencia market-type, erect growth habit, red seed coat, maturity range around 100 days after planting) and IAC-Caiap´o (Runner market-type, prostate growth habit, pink testa, maturity range more than 135 days). From 15 to 90 days after emergence, samples of leaves and stems were harvested, dried, weighted and ground to determine macro and micronutrient concentration. At 75 days after sowing, the cultivar IAC-Caiap´o showed higher contents of N, P, K, Cu, and Zn while IAC-Tatu presented higher concentrations of Ca, Mg, and S. Zn content was higher in conservation tillage than in conventional, mainly in Oxisoil for both of cultivars

Nitrate in groundwater in a recharge area of Guarany aquifer in Brazil.

The region of Ribeirão Preto City located in São Paulo State, southeastern Brazil, is an important sugarcane, soybean and corn producing area. This region is also an important recharge area (Espraiado) for groundwater of the Guarany aquifer, a water supply source for the city and region. It has an intercontinental extension that comprises areas of eight Brazilian states, as well as significant portions of other South American countries like Argentina, Uruguay, and Paraguay, with a total area of approximately 1,200,000 Km2. Due to the high permeability of some soils present in this region, the high mobility of the herbicides and fertilizers applied, and being a recharge area, it is important to investigate the potential transport of applied fertilizers to underlying aquifer. The cultivation sugar cane in this area demands the frequent use of nitrogen as fertilizer. This research was conducted to characterize the potential contamination of groundwater with nitrogen in the recharge area of groundwater. Seven groundwater sample points were selected in the Espraiado stream watershed, during the years of 2005 and 2006. Samples were collected during the months of March, July, and December of each year. Three replications were collected at each site. Groundwater was also collected during the same months from county groundwater wells located throughout the city. The following six wells were studied: Central, Palmares, Portinari, Recreio Internacional, São Sebastião, and São José. Nitrate water samples were analyzed by Cadmium Reduction Method. No significant amount of nitrate was found in the recharge, agricultural, area. However, nitrate levels were detected at concentrations higher than the Maximum Concentration Level (MCL) of 10mg/L in downtown, urban, well located away from agricultural sites with no history of fertilizer or nitrogen application

Soil tillage systems and herbicide leaching in Brazil.

The Guarany aquifer located in South America has a dimension of approximately 1,200,000 Km2 and spreads to areas of eight Brazilian states plus parts of Argentina, Uruguay and Paraguay. The region of Ribeirao Preto City, located in Southeast of Brazil, Sao Paulo State, is a sugarcane, soybean, peanuts, and corn producing area. This region is also an important recharge area to the aquifer. Intensive farming on the area has demanded constant use of herbicides and fertilizers. Triazine herbicides such as atrazine, ametryn, and simazine are used on the area and are known to have potential for groundwater contamination. Currently most of the sugar cane crop is mechanically harvested without burning. This practice allows the straw to decompose in soil, maintain a better soil structure, and interferes with the movement and leaching of solutes. It is a common practice to sow peanuts after sugarcane harvest using no-tillage or conventional planting systems. To evaluate the effects of herbicide leaching into groundwater during notillage planting of peanut after mechanically harvested sugarcane, a soil leaching study using soil columns has been conducted. The results showed a general trend of higher density and lower porosity in soils under no-tillage, mainly at the top layer. The Hydraulic Conductivity determined in soil columns was higher for soils under conventional system than no-tillage, 10.82 and 4.59 cm/h respectively,indicating higher leaching potential for conventional system