Cristiano Alberto de Andrade

Infield greenhouse gas emissions from sugarcane soils in Brazil: effects from synthetic and organic fertilizer application and crop trash accumulation

Bioethanol from sugarcane is becoming an increasingly important alternative energy source worldwide as it is considered to be both economically and environmentally sustainable. Besides being produced from a tropical perennial grass with high photosynthetic efficiency, sugarcane ethanol is commonly associated with low N fertilizer use because sugarcane from Brazil, the worlds largest sugarcane producer, has a low N demand. In recent years, several models have predicted that the use of sugarcane ethanol in replacement to fossil fuel could lead to high greenhouse gas (GHG) emission savings. However, empirical data that can be used to validate model predictions and estimates from indirect methodologies are scarce, especially with regard to emissions associated with different fertilization methods and agricultural management practices commonly used in sugarcane agriculture in Brazil. In this study, we provide in situ data on emissions of three GHG (CO2, N2O, and CH4) from sugarcane soils in Brazil and assess how they vary with fertilization methods and management practices. We measured emissions during the two main phases of the sugarcane crop cycle (plant and ratoon cane), which include different fertilization methods and field conditions. Our results show that N2O and CO2 emissions in plant cane varied significantly depending on the fertilization method and that waste products from ethanol production used as organic fertilizers with mineral fertilizer, as it is the common practice in Brazil, increase emission rates significantly. Cumulatively, the highest emissions were observed for ratoon cane treated with vinasse (liquid waste from ethanol production) especially as the amount of crop trash on the soil surface increased. Emissions of CO2 and N2O were 6.9 kg ha−1 yr−1 and 7.5 kg ha−1 yr−1, respectively, totaling about 3000 kg in CO2 equivalent ha−1 yr−1.

Enhanced-efficiency fertilizers in nitrous oxide emissions from urea applied to sugarcane.

The environmental benefits of producing biofuels from sugarcane have been questioned due to greenhouse gas emissions during the biomass production stage, especially nitrous oxide (NO) associated with nitrogen (N) fertilization. The objective of this work was to evaluate the use of nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4 dimethylpyrazole phosphate (DMPP) and a controlled-release fertilizer (CRF) to reduce NO emissions from urea, applied at a rate of 120 kg ha of N. Two field experiments in ratoon cycle sugarcane were performed in Brazil. The treatments were (i) no N (control), (ii) urea, (iii) urea+DCD, (iv) urea+DMPP, and (v) CRF. Measurements of NO fluxes were performed using static chambers with four replications. The measurements were conducted three times per week during the first 3 mo and biweekly afterward for a total of 217 and 382 d in the first and second seasons, respectively. The cumulative NO-N emissions in the first ratoon cycle were 1098 g ha in the control treatment and 1924 g ha with urea (0.7% of the total N applied). Addition of NIs to urea reduced NO emissions by more than 90%, which did not differ from those of the plots without N. The CRF treatment showed NO emissions no different from those of urea. The results were similar in the second ratoon: the treatment with urea showed NO emissions of 0.75% of N applied N. Application of NIs resulted in a strong reduction in NO emissions, but CRF increased emissions compared with urea. We therefore conclude that both NIs can be options for mitigation of greenhouse gas emission in sugarcane used for bioenergy.

Propriedades químicas do solo e nutrição do eucalipto em função da aplicação de lodo de esgoto

Sewage sludge application in forest plantations is one of the alternatives to solve the problematic final disposal of this residue. This research aimed at evaluating whether biosolids application improves soil fertility and the nutritional status of Eucalyptus grandis seedlings. The trial was installed in 20 cm diameter PVC columns with nine treatments (control, mineral fertilizer and increasing biosolid rates from 10 to 160 t ha-1) in four replications. The experiment lasted 12 months after planting the seedlings. Biosolids had a greater influence on soil acidity than on the other soil chemical properties. N, P and S leaf concentrations were correlated with CEC and soil organic C content. These variables presented significantly higher values at doses of 80 and 160 t ha-1. It was observed that soil organic matter decreased at biosolid doses from 10 to 40 t ha-1. Alkaline biosolids reduced the soil acidity and improved soil fertility, increasing the availability of most nutrients.

QUALIDADE DA MATÉRIA ORGÂNICA E ESTOQUES DE CARBONO E NITROGÊNIO EM LATOSSOLO TRATADO COM BIOSSÓLIDO E CULTIVADO COM EUCALIPTO

SUMMARY : ORGANIC MATTER QUALITY AND CARBON AND NITROGENSTOCKS IN AN OXISOL TREATED WITH BIOSOLIDS ANDCULTIVATED WITH EUCALYPTUS The objective of this study was to determine the effect of application of increasing dosesof an alkaline biosolid on carbon (C) and nitrogen (N) stocks, as well as on the organicmatter quality of an Oxisol cultivated with eucalyptus, after five years of biosolids application.The study was conducted at the Experimental Station of ESALQ/USP, in Itatinga County,Sao Paulo State, Brazil. The experiment was initiated in March 1998 on an area where aseven-year-old Eucalyptus grandis plantation had been harvested and substituted by a newone planted under the minimum cultivation system. Four months later, anaerobic digestedbiosolid with original moisture content was applied over the soil surface and in-betweenplant rows, with no posterior incorporation. Five treatments were evaluated: (a) Control;(b) Mineral Fertilization with N, P, K, B and Zn (Mineral Fert.); (c) 10 t ha

Chemical and microbiological attributes of an oxisol treated with successive applications of sewage sludge

Studies on sewage sludge (SS) have confirmed the possibilities of using this waste as fertilizer and/or soil conditioner in crop production areas. Despite restrictions with regard to the levels of potentially toxic elements (PTE) and pathogens, it is believed that properly treated SS with low PTE levels, applied to soil at adequate rates, may improve the soil chemical and microbiological properties. This study consisted of a long-term field experiment conducted on a Typic Haplorthox (eutroferric Red Latosol) treated with SS for seven successive years for maize production, to evaluate changes in the soil chemical and microbiological properties. The treatments consisted of two SS rates (single and double dose of the crop N requirement) and a mineral fertilizer treatment. Soil was sampled in the 0-0.20 m layer and analyzed for chemical properties (organic C, pH, P, K, Ca, Mg, CEC, B, Cu, Fe, Mn, Zn, Cd, Ni, and Pb) and microbiological properties (basal respiration, microbial biomass activity, microbial biomass C, metabolic quotient, microbial quotient, and protease and dehydrogenase enzyme activities). Successive SS applications to soil increased the macro- and micronutrient availability, but the highest SS dose reduced the soil pH significantly, indicating a need for periodic corrections. The SS treatments also affected soil microbial activity and biomass negatively. There were no significant differences among treatments for maize grain yield. After seven annual applications of the recommended sludge rate, the heavy metal levels in the soil had not reached toxic levels.

CO2, CH4 and N2O fluxes in an Ultisol treated with sewage sludge and cultivated with castor bean

Organic residue application into soil alter the emission of gases to atmosphere and CO2, CH4, N2O may contribute to increase the greenhouse effect. This experiment was carried out in a restoration area on a dystrophic Ultisol (PVAd) to quantify greenhouse gas (GHG) emissions from soil under castor bean cultivation, treated with sewage sludge (SS) or mineral fertilizer. The following treatments were tested: control without N; FertMin = mineral fertilizer; SS5 = 5 t ha-1 SS (37.5 kg ha-1 N); SS10 = 10 t ha-1 SS (75 kg ha-1 N); and SS20 = 20 t ha-1 SS (150 kg ha-1 N). The amount of sludge was based on the recommended rate of N for castor bean (75 kg ha-1), the N level of SS and the mineralization fraction of N from SS. Soil gas emission was measured for 21 days. Sewage sludge and mineral fertilizers altered the CO2, CH4 and N2O fluxes. Soil moisture had no effect on GHG emissions and the gas fluxes was statistically equivalent after the application of FertMin and of 5 t ha-1 SS. The application of the entire crop N requirement in the form of SS practically doubled the Global Warming Potential (GWP) and the C equivalent emissions in comparison with FertMin treatments.

Produtividade e nutrição de mamona cultivada em área de reforma de canavial tratada com lodo de esgoto

The use of sewage sludge (SS) in agricultural soils is one of the most viable forms of recycling this residue. The purpose of this study was to investigate the effect of SS application on castor bean yield and nutrition in a clayey dystrophic Ultisol following a rotation of sugarcane. The treatments tested were four sewage-sludge rates (0, 5, 10, and 20 t ha-1, dry matter) calculated to supply plants with N at amounts of 0, 37.5 kg ha-1, 75 kg ha-1 and 150 kg ha-1; mineral fertilization with N-P2O5-K2O (75-40-80, respectively) and a control without fertilization. Castor bean, cultivar IAC-Guarani, was grown for 180 days, from November 2004 to May 2005. There was a significant (p<0.05) increment of castor bean yield due to SS application. the application of 10 t ha-1 SS resulted in an agronomic efficiency index of 85 %, compared to mineral fertilization. Nitrogen was the most limiting nutrient concerning yield and plant growth and the nitrogen mineralization rate used underestimated the N supplied by SS under field conditions. Applying SS a the studied rates led to an increment of soil Cu and Zn contents, but metal contents in soil and plant tissues still were within the limits established by the environmental legislation.

Carbon sequestration and greenhouse gases emissions in soil under sewage sludge residual effects

The large volume of sewage sludge (SS) generated with high carbon (C) and nutrient content suggests that its agricultural use may represent an important alternative to soil carbon sequestration and provides a potential substitute for synthetic fertilizers. However, emissions of CH4 and N2O could neutralize benefits with increases in soil C or saving fertilizer production because these gases have a Global Warming Potential (GWP) 25 and 298 times greater than CO2, respectively. Thus, this study aimed to determine C and N content as well as greenhouse gases (GHG) fluxes from soils historically amended with SS. Sewage sludge was applied between 2001 and 2007, and maize (Zea mays L.) was sowed in every year between 2001 and 2009. We evaluated three treatments: Control (mineral fertilizer), 1SS (recommended rate) and 2SS (double rate). Carbon stocks (0-40 cm) were 58.8, 72.5 and 83.1 Mg ha–1in the Control, 1SS and 2SS, respectively, whereas N stocks after two years without SS treatment were 4.8, 5.8, and 6.8 Mg ha–1, respectively. Soil CO2 flux was highly responsive to soil temperature in SS treatments, and soil water content greatly impacted gas flux in the Control. Soil N2O flux increased under the residual effects of SS, but in 1SS, the flux was similar to that found in moist tropical forests. Soil remained as a CH4sink. Large stores of carbon following historical SS application indicate that its use could be used as a method for carbon sequestration, even under tropical conditions.

O alto teor de silício no solo inibe o crescimento radicular de cafeeiros sem afetar as trocas gasosas foliares

Several studies have confirmed the benefits of silicon (Si) for crop growth. The purpose of this study was to evaluate the effects of Si on the initial growth of coffee plants cv. Catuai Vermelho. This study was carried out with potted plants grown in a greenhouse, without water deficiency. Dry matter partitioning of roots, stems and leaves as well as the chemical composition of plant tissues and soil and leaf gas exchange were evaluated in plants treated with 0 (control), 1.5 and 6 Mg ha-1 of calcium silicate. The experiment was arranged in a randomized block design, with three treatments, and 3, 4 or 18 replications, depending on the evaluated variable. Each plot consisted of one plant. Regarding height and total dry matter, the plant growth was satisfactory in all treatments, with daily increases similar to the expected for well-fertilized coffee plants. The treatments resulted in increased soil and plant Ca and Si concentrations. Considering that only leaf Ca concentration was affected by treatments and its concentration was not deleterious, the observed responses are consequences of the high soil Si concentrations. Root dry matter of plants treated with 6 Mg ha-1 of calcium silicate decreased and the ratio between shoot and root dry matter increased 130 days after the beginning of the experiment. Despite the decreases in root growth and in Ca use efficiency, leaf CO2 assimilation and stomatal conductance of the coffee plants were not affected. In summary, high soil concentrations of calcium silicate decrease the root growth of Arabica coffee plants cv. Catuai Vermelho; however, the functionality and development of shoots in well-nourished plants growing under well-watered conditions are not affected.

Mineralização do carbono e do nitrogênio no solo após sucessivas aplicações de lodo de esgoto

The objective of this work was to evaluate the dynamics of carbon mineralization and the soil capacity in providing nitrogen after successive applications of sewage sludge, as well as to determine their relation with the mineralization rate of the sludge previously applied. The experimental area received for seven years the following treatments: 80 kg ha ‑1 per year of mineral N (L0); and 10 or 20 Mg ha ‑1 per year of sewage sludge (L1 and L2, respectively). Soil samples (0-20 cm) were taken one year after the last application of the treatments. Samples received sewage sludge doses corresponding to 0, 120, and 240 kg ha ‑1 of N and were incubated in laboratory for more than 100 days, with determination of C‑CO2 emission and inorganic soil N content. The mineralization of C and N was more influenced by the previous use of sludge than by the incubated doses. The nitrogen mineralization rate (NMR) reduced from 16%, on L0, to 11% on L1 and 8% on L2. However, this reduction did not result in lower N availability on the system, since there was an increase of the potentially mineralizable nitrogen (N0) in L1 and L2. Therefore, the NMR is not an adequate parameter for calculating the sewage sludge dose to be applied on areas previously treated with the residue, since it underestimates the system capacity of providing N. In this case, the use of N0 should be considered.