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Title: Sidedress nitrogen application rates to sorghum intercropped with tropical perennial grasses

Author
item MATEUS, G - Sao Paulo State University (UNESP)
item CRUSCIOL, C A - Sao Paulo State University (UNESP)
item PARIZ, C - Sao Paulo State University (UNESP)
item BORGHI, E - Embrapa
item COSTA, C - Sao Paulo State University (UNESP)
item MARTELLO, J - Sao Paulo State University (UNESP)
item Franzluebbers, Alan
item CASTILHOS, A - Sao Paulo State University (UNESP)

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2015
Publication Date: 1/14/2016
Citation: Mateus, G.P., Crusciol, C.C., Pariz, C.M., Borghi, E., Costa, C., Martello, J.M., Franzluebbers, A.J., Castilhos, A.M. 2016. Sidedress nitrogen application rates to sorghum intercropped with tropical perennial grasses. Agronomy Journal. 108:433-447.

Interpretive Summary: Evaluation of diverse cropping systems is needed to develop more sustainable production systems, particularly in warm-humid regions of the world. A USDA-ARS scientist in Raleigh, North Carolina collaborated with scientists at São Paulo State in Brazil to make evaluations of sorghum grown in monoculture or intercropped with common forage grasses in the tropical region of Brazil, palisade grass and guinea grass. Nitrogen fertilizer was applied at different rates at sidedress to determine optimum nutrient supply for these intercropped systems. Intercropping sorghum with palisade grass led to high grain yield and forage dry matter production. Ecological and economical responses were optimized with sufficient nitrogen input and intercropping of grain and forage. These results will be useful in designing more sustainable mixed-use grain and forage production systems in warm-humid regions throughout the world.

Technical Abstract: Intercropping sorghum [Sorghum bicolor (L.) Moench] with tropical grasses and using the appropriate rate of sidedress nitrogen (N) application can maximize grain yield and revenue, and can improve land-use efficiency. The effects of monocropped sorghum or sorghum intercropped with palisade grass [Urochloa brizantha cv. Marandu] or guinea grass [Panicum maximum cv. Mombaça] and sidedress N application rates of 0, 50, 100 and 200 kg/ha on leaf nutrient concentration, sorghum grain yield, revenue and land-use efficiency were investigated over three growing seasons at Botucatu, São Paulo State, Brazil on a clay, kaolinitic, thermic Typic Haplorthox. Sorghum with guinea grass had lower leaf N, P, and K concentrations and lower grain density, shoot dry matter, and grain yield than monoculture sorghum and sorghum with palisade grass at all sidedress N rates. Monoculture sorghum and sorghum with palisade grass at 200 kg/ha of sidedress N resulted in greatest grain yield (3.80 and 3.81 Mg/ha, respectively). Forage dry matter production and crude protein of tropical perennial grasses were higher as a function of the sidedress N rate. Sorghum with guinea grass resulted in negative net profits for all sidedress N rates. Monoculture sorghum and sorghum with palisade grass (independent of sidedress N rates) resulted in similar net profits (approximately US$ 85 and 60/ha, respectively). Sorghum with palisade grass using 200 kg/ha of sidedress N rate resulted in a higher land equivalent ratio and relative N yield (1.27 and 123%, respectively) than sorghum with guinea grass (0.96 and 107%, respectively). Sorghum with palisade grass using 200 kg/ha of sidedress N rate is the best option for increasing sorghum grain yield, revenue and forage dry matter production from autumn to part of the spring and for improving land-use efficiency.