Short-term CO2-C emissions from soil prior to sugarcane (Saccharum spp.) replanting in southern Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

On the spatial and temporal dependence of CO2 emission on soil properties in sugarcane (Saccharum spp.) production

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparo do solo e emissão de CO2, temperatura e umidade do solo em área canavieira

Soil tillage is one of the agricultural practices that may contribute to increase the loss of carbon through emission of CO2 (FCO2). The aim of this study was to investigate the effect of three soil tillage systems on FCO2, soil temperature and soil moisture in a sugarcane area under reform. The experimental area consisted of three tillage plots: conventional tillage (CT), conventional subsoiling (CS), and localized subsoiling (LS). FCO2, soil temperature and soil moisture were measured over a period of 17 days. FCO2 showed the highest value in CT (0.75 g CO2 m(-2) h(-1)). Soil temperature presented no significant difference (p > 0.05) between LS (26.2 degrees C) and CS (25.9 degrees C). Soil moisture was higher in LS (24%), followed by CS (21.8%) and CT (18.3%). A significant correlation (r = -0.71; p < 0.05) between FCO2 and soil temperature was observed only in CT. The conventional tillage presented a total emission (2,864.3 kg CO2 ha(-1)) higher than the emissions observed in CS (1,970.9 kg CO2 ha(-1)) and LS (1,707.7 kg CO2 ha(-1)). The conversion from CT to LS decreased soil CO2 emissions, reducing the contribution of agriculture in increasing the concentration of greenhouse gases in the atmosphere.

Vereda and Murundu wetlands and changes in Brazilian environmental laws: challenges to conservation

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estoque de carbono e atributos físicos de um Latossolo em cronossequência sob diferentes manejos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Rentabilidade na semeadura cruzada da cultura da soja

Soybean cross-seeding tillage came from better spatial arrangement of plants per area, so some producers have opted for this tillage system, which consists in seeding the area in two steps, forming a chessboard with perpendicular lines of tillage. This study aims to analyse the soybean productivity and production costs when it planted in different dispositions of crossed tillage. The experiment was conducted during the harvests 2011/2012 and 2012/2013 at Lageado Farm of the FCA/UNESP, Botucatu-SP, in an area cultivated under no-tillage. The experimental design was in randomized block with five treatments and eight replications. The treatments were: seeding in parallel rows with recommended fertilization and recommended plant population (conventional); cross-seeding with doubled fertilization and doubled plant population; cross-seeding with recommended plant population and doubled fertilization; cross-seeding with doubled plant population and recommended fertilization; cross-seeding with fertilization and recommended plant population. The results showed statistical difference among the treatments, with increased productivity for the cross-seeding with doubled plant population and recommended fertilization. However the conventional tillage with parallel lines shows higher net earnings than soybean cross-seeding, being more profitable for producer.

Prediction of soil shear strength in agricultural and natural environments of the Brazilian Cerrado

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ideal desiccation periods of Urochloa ruziziensis for a no-till sunflower crop

Sowing crops following cover crops on forage may cause injuries and productivity reduction, due reasons as allelopathy or glyphosate residues. The objective of this study was to evaluate the influence of differing periods between cover crop (Urochloa ruziziensis) desiccation with glyphosate and sunflower (Aguara 4) sowing in a no-tillage system on crop development and productivity. Two assays were performed in two seasons, one in pots and the other in a field. Treatments in field assay consisted on 5 desiccation times of U. ruziziensis (with an application of glyphosate at 1.08 kg ae ha(-1)) preceding the sowing of no-till sunflower (0, 3, 7, 10 and 30 days). At the pot assays, 6 times were studied: 0, 3, 7, 10, 15 and 20 days between cover crop desiccation and sunflower sowing. A control without cover crop was also included in this assay. Biometric evaluations were performed at the vegetative stage and at harvest. As the period between U. ruziziensis desiccation and sunflower sowing was shortened, achene production in sunflower was exponentially reduced. Glyphosate application at 3 or 0 days pre sowing diminished sunflower development and achene production by approximately 30% compared to desiccation periods greater than 7 days.

Managing soil carbon for multiple ecosystem benefits positive exemplars: Latin America (Brazil and Argentina)

Agriculture provides food, fibre and energy, which have been the foundation for the development of all societies. Soil carbon plays an important role in providing essential ecosystem services. Historically, these have been viewed in terms of plant nutrient availability only, with agricultural management being driven to obtain maximum benefits of this soil function. However, recently, agricultural systems have been envisioned to provide a more complete set of ecosystem services, in a win-win situation, in addition to the products normally associated with agriculture. The expansion and growth of agricultural production in Brazil and Argentina brought about a significant loss of soil carbon stocks, and consequently the associated ecosystem services, such as flooding and erosion control, water filtration and storage. There are several examples of soil carbon management for multiple benefits in Brazil and Argentina, with new soil management techniques attempting to reverse this trend by increasing soil carbon (C) stocks. One example is zero tillage, which has the advantage of reducing CO2 emissions from the soil and thus preserving or augmenting C stocks. Crop rotations that include cover crops have been shown to sequester significant amounts of C, both in Brazilian subtropical regions as well as in the Argentinean Pampas. Associated benefits of zero tillage and cover crop rotations include flood and erosion control and improved water filtration and storage. Another positive example is the adoption of no-burning harvest in the vast sugarcane area in Brazil, which also contributes to reduced CO2 emissions, leaving crop residues on the soil surface and thus helping the conservation of essential plant nutrients and improving water storage.

Doses, fontes e épocas de aplicação de nitrogênio influenciando teores de clorofila e produtividade do trigo

To achieve high wheat yield, correct management of N fertilization and the use of high yield potential cultivars are necessary. The aim of this study was to evaluate the effects of different application rates and sources of N, applied totally at sowing or in topdressing, on grain yield and yield components of two irrigated wheat cultivars under a no-till system, grown in a Cerrado (Brazilian tropical savanna) region of low altitude. A randomized block design was used in a 5 x 3 x 2 x 2 factorial arrangement with three replications, combining five levels of N (0, 50, 100, 150, and 200 kg ha(-1)), three sources of N (Entec (R), ammonium sulfate, and urea), and two application times (at sowing, near the rows, or in topdressing) in two wheat cultivars (IAC 370 and Embrapa 21). The wheat cultivars had similar grain yields. There was no difference among the sources of N for grain yield and yield components. The N applied totally at sowing did not differ from the traditional application at sowing and in topdressing for production of irrigated wheat in no-tillage. The increase in application rates of N increased the leaf N contents and chlorophyll, plant height, and the number of ears per m(2). Grain yield of the wheat cultivars IAC 370 and Embrapa 21 increased up to the application rates of 134 and 128 kg ha(-1) of N, respectively, regardless of application time and source of N. The positive correlation between chlorophyll leaf content and grain yield in accordance with N fertilization levels indicates that N fertilization in topdressing can be recommended based on SPAD readings of leaf chlorophyll performed at 38 days after wheat plant emergence.

Desempenho e uso eficiente da terra de modalidades de consorciação com milho e forrageiras

This study was developed with the aim of evaluating the performance and land use efficiency of different arrangements of intercropping with maize and forage. The field experiment was conducted in Tangar da Serra/MT. The experimental design was a randomized block in factorial scheme 3x2 + 1, were as three arrangements of intercropping, two species of forage and an additional treatment with maize monoculture in four replication. In maize monoculture and intercropping were evaluated: plant height and ear insertion height, plant population, weight of 100 grains, productivity, number of grain rows and number of grain per row. In forages intercropping with maize were evaluated plant population and dry matter accumulation. The arrangements with Maize + Forage sown in the line and Maize + Forage sown in two rows between rows with the species Urochloa hybrid promoted best corn yields. The modality and species affect both the productivity of maize as forages species. Grain yield of maize is higher in monoculture. The higher dry matter accumulation of Urochloa hybrid occurs in the Maize + Forage sown in one row between rows, while, for the Urochloa brizantha the arrangements studied do not affect their yields. The arrangement with best land use efficiency is Maize + Forage sown in two rows between rows for both study forage species.

Alterações na estabilidade de agregados de latossolo e argissolo em função do manejo, na entrelinha da seringueira (Hevea brasiliensis)

A trial was carried out with the purpose of evaluating the effect of different management systems applied between the rows of rubber trees (Hevea brasiliensis) on the aggregate stability in water of Dark Red Latosol, with clayey texture from the Municipality of Jaboticabal (SP) and Yellow Red Podzolic, sandy/medium texture fromthe Municipality of Tabapua (SP). The treatments consisted of disk harrowing, Pueraria phaseoloides and mowing. The soil samples were withdrawn after seven years of application of these management systems from depths of 0-0.1, 0.1-0.2, 0.2-0.3, and 0.3-0.4 m. The stability of the aggregates was obtained in sieves with size classes of 8-4, 4-2, 2-1, 1-0.5, 0.5-0.125, and < 0.125 mm. The Pueraria phaseoloides gave a significant difference regarding the distribution of the aggregates on the superficial layer (10 cm) when compared to the other management systems, presenting a higher distribution of larger sized aggregates on the Dark Red Latosol. The tillage management for this same depth presented higher values of small sized aggregates on both soils. The organic matter on the soils showed a direct and significant relation to the stability of the larger sized aggregates and an inverse relation with the stability of the smaller sized aggregates.

The effects of land use and soil management on the physical properties of an Oxisol in Southeast Brazil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Early growth of common bean cropped over ruzigrass residues

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)