Improvement of tall wheatgrass biomass yield and quality by intercropping with two legumes

MENGHINI, MARIANO; ARELOVICH, HUGO MARIO; LAGRANGE, SEBASTIAN; QUNITANA, MATIAS; GALASSI, ALFREDO

Indianapolis

Congreso; ADSA-ASAS-CSAS Joint Annual Meeting 2013; 2013

ADSA-ASAS-CSAS

Tall wheatgrass (Thinopyrum ponticum, Pdop.) is a drought resistant perennial grass seeded in Argentina on saline soils for cattle grazing. Intake and nutritional quality are the main constraints to animal performance. The objective was to evaluate the effect of intercropping legumes in a stand of tall wheatgrass on dry matter (DM) availability (DMA) and yield (DMY), as well as quality of the grass. Treatments were: CON (control); HV, intercropping hairy vetch (Vicia villosa) or WS, white sweetclover (Melilotus albus). On March 27, 2012 a chisel plow plus a land roller were run on plots marked on the tall wheatgrass paddock. Two days later HV and MA were seeded at 13 and 7 kg/ha in 3 replicates per treatment. Two cuts were performed in spring upon all treatments at fixed dates: 176 (C1) and 219 (C2) d after seeding. Neutral and acid detergent fiber (NDF and ADF), acid detergent lignin (ADL) and in vitro DM digestibility (IVDMD) were measured by random samples of 1 m2 cut at 3 cm height on each plot. The disk method was used to estimate DMA at beginning of internodes elongation. All data was analyzed by ANOVA and means were separated by LSD (α = 0.05), except for DMA which was subjected to regression analysis. In C2, DMY increased (P = 0.02; SE = 145) for VH (1354 kg/ha) compared with CON (597 kg/ ha). Overall DMY were: 1521, 1792 and 2583 kg/ha for CON, SW and VH respectively (P = 0.09; SE = 296). A higher DM content was observed for CON = 47.6% compared with 32.6 and 33.7% for SW and HV, respectively (P = 0.04; SE = 3.6). Nonsignificant trends for NDF and IVDMD (P = 0.07 and 0.13, respectively) indicated a reduction in cell wall content of tall wheatgrass and improvement of IVDMD because of legume intercropping. No differences were observed for ADF and ADL. DMA = 129.51x ? 453.92; 106.1x + 346.94 and 108.3x ? 231.62, with R2 = 0.91, 0.63 and 0.60 (P < 0.01) for CON, VH and SW, respectivel, were the calculated regression equations and respective correlation coefficients. These results suggest that overall DMY and quality of tall wheatgrass can be improved by legume intercropping. DMA seems more precisely estimated in pure stands of tall wheatgrass.