Utilization of nitrogen from green manure and mineral fertilizer by sugarcane

Abstract

Given their potential for biological nitrogen fixation, legumes used as green manure are an alternative source of nitrogen to crops, and can supplement or even replace mineral nitrogen fertilization. The utilization of nitrogen by sugarcane (Saccharum spp.) fertilized with sunn hemp (Crotalaria juncea L.) and ammonium sulphate (AS) was evaluated using the ), isotopic abundance of N (atoms % 15 N) in leaf +3 samples, and sugarcane productivity were used to calculate cumulative N, nitrogen in the plant derived from the fertilizer-Ndff (% and kg ha -1 ), as well as percent recovery of fertilizer N (R%). Sugarcane was analysed and pol and total recovered sugar calculated. The highest Ndff percentages were observed eight months after sugarcane planting for treatments containing green manure without mineral N, and green manure with mineral N, at 15.3 and 18.4%, respectively. The best nitrogen recovery was observed during harvest, 18 months after planting; the treatment containing mineral fertilizer showed 34.4% recovery, while the sum between mineral N plus green manure N showed 40.0%. Treatments containing green manure plus mineral N changed soil attributes, by increasing Ca and Mg contents, sum of bases, pH, and base saturation, and decreasing potential acidity. In the plant, those treatments increased Ca and K contents. ) e da abundância isotópica de N (% em átomos de 15 N) das amostras de folhas +3 e da produtividade da cana-de-açúcar, foram calculados o N-acumulado, nitrogênio na planta proveniente do fertilizante-NPPF (% e kg ha -1), e a recuperação percentual do N do fertilizante (%R). Foram realizadas análises tecnológicas da cana e calculados o pol (%) e açúcares totais recuperados. As maiores porcentagens de NPPF foram encontradas após oito meses de plantio da cana para os tratamentos com adubo verde sem N-mineral e adubo verde com N-mineral, respectivamente 15,3 e 18,4%. A maior recuperação do nitrogênio foi encontrada na colheita, dezoito meses após o plantio, sendo que o tratamento com fertilizante mineral apresentou 34,4% e na soma N-mineral mais N-adubo verde apresentou 40,0%. Os tratamentos com adubo verde mais N-mineral alteraram atributos do solo e da planta, promovendo aumento nos teores de Ca e Mg, soma de bases e saturação de bases e pH, com declínio na acidez potencial no solo, bem como aumento nos teores de Ca e K na parte aérea. Palavras-chave: Saccharum spp., crotalária júncea,

Crop rotation biomass and arbuscular mycorrhizal fungi effects on sugarcane yield

“…Sakai et al (2007) worked with velvet bean and also reported soil fertility improvement, with the decrease of potential acidity, increase in Ca and Mg availability, and increase in base saturation (V%). Increases in Mg concentration were also found by Ambrosano et al (2005) who worked with sunn hemp as green manure. The presence of organic acids in decomposing plant residues can help Mg movement in the soil (Franchini, 2001).…”

“…The high AMF infection rate, which helps the uptake of micronutrients (Table 6), may explain the high amounts of Zn returned to the soil when sunflower was grown before sugarcane. There is an increasing utilization of sunflower as a crop rotation with sugarcane in Brazil, due to its use for silage, seed oil production, and to its potential as a feedstock for biodiesel (Porto et al, 2008) The amounts of N in the above-ground parts of sunn hemp (Table 4) were relatively low compared to those of Caceres and Alcarde (1995), who reported the extraction of up to 230 kg ha -1 of N, and to those of Ambrosano et al (2005), who found 196 kg ha -1 of N. However, the amounts of N returned to the soil are directly related to the nutrient concentration in the plant, which varies with the local potential for biological nitrogen fixation (BNF) and with the growth stage of the crop at the time of cutting, and with the biomass yield, which is affected by the weather, soil, and crop growing conditions. Perin et al (2006) found substantial amounts of N derived from BNF present in the above ground parts of sunn hemp (57.0%) grown isolated and 61.1% when intercropped with millet (50% seeded with each crop).…”

“…Leguminous plants can accumulate over 5 t ha -1 of dry mass during a short period of time during the summer and take up large amounts of N and K. Most of this N comes from the association of legumes with rhizobia. In this way crop rotation with legumes can replace partially or totally N mineral fertilization of sugarcane, at least for the first ratoon (Albuquerque et al, 1980;Ambrosano et al, 2005).…”

Contribution of nitrogen from sugarcane harvest residues and urea for crop nutrition

“…This composition affords intense N immobilization by the soil microbial biomass and a slow net mineralization of C and N. Likewise, the recovery rates of N from crop residues incorporated into the soil varied from 2 % to 15 % of the total N contained in such residues (Ambrosano et al, 2005;Basanta et al, 2003;Chapman et al, 1992;Gava et al, 2005;Meier et al, 2006;Ng Kee Kwong et al, 1987;Trivelin et al, 2002;Vitti et al, 2010).…”

Transformações do nitrogênio no solo e a resposta da cana-planta à adubação nitrogenada em função da rotação com crotalária

“…Essa prática não interfere na brotação da cana e promove aumento significativo nas produções de cana-de-açúcar em pelo menos dois cortes; protege o solo contra erosão e evita a multiplicação de ervas daninhas (AMBROSANO et al, 2005). Na região Centro-Sul do Brasil, a prática que tem sido amplamente utilizada é o plantio de leguminosas como…”