RENDIMIENTO Y EXTRACCIÓN DE NITRÓGENO, FÓSFORO Y POTASIO DE MAÍZ FORRAJERO EN SURCOS ESTRECHOS * YIELD AND NITROGEN, PHOSPHORUS AND POTASSIUM UPTAKE OF FORAGE MAIZE IN NARROW ROWS

Planting on narrower rows rather than the conventional at 76 cm can increase yield and nutrient uptake of forage maize. The objective of this study was to determine the effect of row spacing on dry matter yield and content of N, P and K of maize cv. 3025W. The study was carried out in 1999 and 2000 in the Campo Experimental La Laguna near Matamoros, Coahuila, Mexico (25o 32' N, 103o 14' O, and 1150 masl). Four row widths were tested: 38, 50 and 76 cm single row and beds at 105 cm double row, all with 11.2 plants m 2 . A complete random block design with four replications was used. Seed yield, total dry matter, dry matter partitioning, harvest index, LAI and total N, P and K uptake were determined. Dry matter yield obtained with the 38 cm single row and 105 cm double row was higher than the obtained with the conventional single row 76 cm by 14 and 17%, respectively, which was related to a higher LAI and dry matter partitioning to vegetative organs, with no significant reduction of the harvest index. N and K uptake increased 36 and 93 kg ha -1 , respectively, in rows at 38 cm as compared with the conventional row spacing, mainly due to a higher dry matter yield per ha.