Residual biomass potential of commercial and pre-commercial sugarcane cultivars

Sugarcane (Saccharum spp.) is an efficient and sustainable alternative for energy generation compared to non-renewable sources. Currently, during the mechanized harvest process, the straw left in the field can be used in part for the second generation ethanol and increasing the electric energy production. Thus, this study aimed to provide information on the potential for residual biomass cultivars of sugarcane cropping system. This study provides the following information: yield of straw, depending on the calculated leaf area index and the number of tillers per linear meter; primary energy production of several sugarcane genotypes; contribution of dry tops and leaves; biomass yield; and evaluation of fiber, cellulose, hemicellulose and lignin. Preliminary results obtained by researchers of the State of São Paulo, Brazil, and reCviews related studies are presented. The results suggest that the production of sugarcane straw content varies according to the cultivars; the greater mass of sugarcane straw is in the top leaves and that the potential for the crude energy production of sugarcane per area unit can be increased using fiber-rich species or species that produce more straw. The straw indexes was shown to be a good indicator and allow the estimation of straw volumes generated in a sugarcane crop. The cellulose, hemicellulose and lignin composition in sugarcane is distinct among varieties. Therefore, it is possible to develop distinct biomass materials for energy production and for the development of sugarcane mills using biochemical processes and thermal routes

Avaliação de atributos físicos e estoques de carbono e nitrogênio em solos com queima e sem queima de canavial

Brazil is the world's largest sugarcane producer, so changes in sugarcane management in Brazil can affect the environment to a great extent. During almost one century, studies were carried out in cropping systems involving pre-harvest burning of aerial sugarcane residues. Nowadays the green trash management of sugarcane residues has become a common practice, although the effects are still poorly documented. The objective of this work was to compare topsoil carbon and nitrogen stocks, aggregation and bulk density in Brazilian sugarcane plantations where aerial residues were either burned (Cq) or left on the soil surface (Sq) after harvest. The study was carried out in three plantations, one on a clayey soil (Latossolo Vermelho, LVdf i.e. Typic Hapludox) and two on sandy soils (Argissolo Vermelho-Amarelo, PVAd, i.e. Typic Hopludult, and Neossolo Quartzarenico, RQo, i.e. Quartzpsamment). On each plantation, the experimental design included six replications per treatment. After three crops, the accumulated aerial residue biomass in Sq treatment amounted to 40 t ha(-1) of DM from which 4.5 and 3.6 t ha(-1) of DM (i.e. 11 and 9 %) were still present at the soil surface in LVdf and RQo, respectively. This represented 1.60 and 1.35 t ha(-1) of C and 0.022 and 0.021 t ha(-1) of N, respectively. As a result, soil carbon at a 0-20 cm depth increased by 6.3 and 4.7 t ha(-1) in LVdf and RQo, respectively. Over the three-year period, the rate of carbon sequestration in the litter and topsoil in the Sq treatment was 2.63 and 2.02 t ha(-1) yr(-1) in LVdf and RQo, respectively. Topsoil content of stable macroaggregates was also higher with Sq than with Cq: 814 vs. 693 g kg(-1) in LVdf and 516 vs, 420 g kg(-1) in RQo, respectively. On the other hand, Sq caused topsoil compaction (PVAd and RQo) due to the mechanized harvest system. In the Brazilian soils under study, green trash management of sugarcane residues improved the topsoil properties and promoted carbon and nitrogen sequestration in the litter and topsoil

Dinâmica do herbicida amicarbazone (Dinamic) aplicado sobre palha de cana-de-açúcar (Saccarum officinarum) Performance of amicarbazone applied on sugarcane straw

O objetivo deste trabalho foi estudar a dinâmica do herbicida amicarbazone (Dinamic) aplicado sobre palha de cana-de-açúcar deixada sobre o solo, em sistema de cana crua. Três ensaios foram realizados para avaliar a dinâmica desse herbicida aplicado sobre diferentes quantidades de palha de cana-de-açúcar, em diferentes intervalos de tempo e volumes de simulação de chuvas após aplicação do herbicida. No primeiro ensaio, foi avaliada a interceptação do herbicida por 0, 1, 2,5, 5, 7,5, 10, 15 e 20 t de palha de cana-de-açúcar ha-1. A lixiviação do herbicida em 5, 10, 15 e 20 t de palha ha-1 foi avaliada sob simulação de chuva de 2,5, 5, 10, 15, 20, 35 e 65 mm, um dia após a aplicação (DAPC) do segundo ensaio. As chuvas foram acumulativas, aplicando-se de 2,5 em 2,5 mm. No terceiro ensaio, foi avaliado o efeito dos intervalos de tempo entre a aplicação do herbicida e a primeira chuva na lixiviação do herbicida Dinamic (0, 1, 7, 15 e 30 dias) em 10 t de palha ha-1, em função das mesmas precipitações simuladas no segundo ensaio. Nos segundo e terceiro ensaios foi realizada uma simulação de 20 mm em intensidade de 115 mm h-¹ aos 7 e 14 dias após as primeiras chuvas (DAPC). Os resultados obtidos no segundo e terceiro ensaios foram ajustados pelo modelo de Mitscherlich (Y = a * (1-10-c * (b + x))). A quantificação do herbicida foi realizada por cromatografia líquida de alta eficiência. Quantidades de palha iguais ou superiores a 5 t ha-1 apresentam interceptação quase que total do herbicida no momento da aplicação, sendo nula a transposição. Com o aumento da quantidade de palha, ocorreu diminuição na quantidade de herbicida lixiviado pela ação da chuva simulada, principalmente para valores de 15 e 20 t de palha de cana-de-açúcar ha-1. Quanto maior o intervalo de tempo entre a aplicação do herbicida e a primeira chuva, menor é a lixiviação total do produto. Em relação às chuvas aos 7 e 14 DAPC, no segundo e terceiro ensaios, foram observadas pequenas quantidades extraídas do herbicida, considerando-se que grande parte do amicarbazone foi lixiviada com as primeiras chuvas, que indicaram que os primeiros 20 mm de chuva simulada foram importantes para lixiviação da maior parte do amicarbazone (Dinamic) retido pela palha no momento da aplicação.<br>In order to better understand the dynamics of the herbicide amicarbazone (Dinamic) applied on sugarcane straw left on the soil under the crude cane system, three assays were carried out to evaluate the performance of this herbicide applied on different amounts of sugarcane straw in different periods and under different rainfall intensities after its application. In the first assay, herbicide interception was assessed by 0, 1, 2.5, 5, 7.5, 10, 15 and 20 t ha-1 of straw. In the second assay, herbicide leaching through 5, 10, 15 and 20 t ha-1 of straw was evaluated under rain simulation equivalent to 2.5 up to 65 mm rain, one day after application (DAA). On the third assay, the effect of the time intervals between herbicide application and the first rain on herbicide leaching (0, 1, 7, 15 and 30 days) on the straw (10 t ha-1) was evaluated under the same rainfall amounts simulated in the second study. For the second and third assays an additional simulation of 20 mm at 07 and 14 days after the opening rains (DAOR) was carried out. The results obtained in second and third assays was adjusted by the Mitscherlich model (Y=a*(1-10&#094;(-c*(x+b)))). The herbicide was quantified by HPLC. The results from the first assay demonstrated that straw amounts equal or superior to 5 t ha-1 present an interception almost equivalent to the total of the applied herbicide with transposition being null. In the second assay, it can be observed that the higher the amount of straw, the smaller the total amount leached, mainly for 15 and 20 t ha-1. In the third assay, the results indicated that the longer the time interval between herbicide application and first rain, the smaller the total leaching of the product by maximum precipitation (65 mm). With regard to rainfall at 7 and 14 DAOR in the second and third assays, small amounts extracted were observed, considering that a great part of amicarbazone was leached with the first rains, indicating that the first 20 mm of simulated rain were important for most amicarbazone leaching retained by the straw during application