Abstract
Sugarcane is the most promising among renewable biofuel-producing crops. An adequate availability of water and nutrients, especially nitrogen (N), is of utmost importance. From the hypothesis that the source and the rate of N fertilization influence the N use efficiency of an irrigated soil–sugarcane system, this study aimed to evaluate the stalk and crop residues (pointer and leaves) yield, as well as the N utilization, from different rates of ammonium nitrate and urea by irrigated sugarcane in the cane plant cycle, using an 15N isotopic dilution technique. The soil used for the experiment was an Oxisol (Rhodic Haplustox) Cerrado (savannah) phase. The experiment was carried out at a farm of the Raízen Mill, which was located in the municipality of Jataí, Goias State, Brazil. The sugarcane variety IACSP95–5000 was used in a randomized block design, with three replicates, four N rates (30, 60, 120, and 180 kg ha−1), and two fertilizer sources labeled with 15N isotopes (urea and ammonium nitrate). The average value for N utilization was 60.17% for the ammonium nitrate source and 44.95% for urea. The responses in the percentage and quantity of N in the sugarcane from the fertilizer increase with the increasing N rate. The soil was the main N source for sugarcane. The higher stalk and pointer yield was recorded at the average rate of 143.61 kg N ha−1. Further studies are needed to evaluate the residual effect of N in the next cycles.
Highlights
Sugarcane (Saccharum spp.) is socio-economically a very important crop for Brazil
The Brazilian Cerrado (Savannah) area comprises about 204.7 million hectares, which is equivalent to 23.3% of the country land, being the main area for expanding of sugarcane cropping in Brazil [1]
It is observed that the Npdfs was 346.16 and 373.75 kg N ha−1 in the doses of 115.19 and 123.25 kg N ha−1, corresponding to increases of up to 68.77% and 54.13%, respectively, for ammonium nitrate and urea (Figure 3B). These results show that of the amount of N accumulated by sugarcane, there was a smaller contribution of N from the fertilizer when compared to N derived from the native N soil
Summary
Sugarcane (Saccharum spp.) is socio-economically a very important crop for Brazil. It is considered one of the main agricultural commodities grown in tropical and subtropical regions. The Brazilian Cerrado (Savannah) area comprises about 204.7 million hectares, which is equivalent to 23.3% of the country land, being the main area for expanding of sugarcane cropping in Brazil [1]. These data justify studies that use tools such as irrigation and nitrogen fertilization, as the proper management of irrigation and nitrogen fertilization promotes an increase in the productive potential of sugarcane
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