Silage from high protein value white corn (Zea mays L.) with and without ears associated with two annual legumes, lablab (Lablab purpureus L.) and sunn hemp (Crotalaria juncea L.)

Abstract

In this study we evaluated the dry matter yield (DMY) and botanical composition of high protein value (QPM) white maize (Zea mays L.) with and without ear removal and associated or not with the annual legumes lablab (Lablab purpureus L.) and sunn hemp (Crotalaria juncea L.), and determined the nutritional value and products of fermentation of silage of these associations. The experiment was conducted in the Experimental Substation at Isabela, Puerto Rico, between January and April 2010 in an Oxisol soil. Lablab and sunn hemp were intercropped with white QPM corn in a randomized complete block design with six treatments and four replications. Ears with grain in the milky stage were removed from the plant at 90-d post seeding; the next day the crop was ensiled in three of the treatments [Monoculture (CWOE), associated with lablab (CLWOE) and with crotalaria (CCWOE)]. There were three analogous treatments of corn with ears present (CE, CLE and CCE). Among the latter, DMY increased with intercropping from 9,890 kg/ha (CE) to 11,256 kg/ha (CLE) and 14,786 kg/ha (CCE) whereas among the treatments without ears the increases were from 7,270 kg/ha (CWOE) to 8,667 kg/ha (CLWOE) and 10,641 kg/ha (CCWOE), thus indicating DMY losses of 2,620 kg/ha, 2,589 kg/ha and 4,145 kg/ha as a result of ear removal, for the three respective comparisons. A greater benefit to DMY occurred when sunn hemp was the intercrop (4,134 kg/ha) compared with that of lablab (1,382 kg/ha). Intercropping with sunn hemp was also more effective in reducing the proportion of weeds in the crop than with lablab (CE, 20.5%; CLE, 17.1%; CCE, 9.9%). Relative to monoculture silage, the intercropped legumes resulted in a slight reduction in dry matter (26.6 to 25.9%), but an increase is crude protein (CP) (10.0 to 11.9%) (P < 0.05). The neutral detergent fiber content of the silages was not affected, but acid detergent fiber increased from 32.9% in monoculture to 38.3% when intercropped with legume; this effect was more pronounced in the absence of ears. Corn-legume intercropping benefited weed control and increased DMY in the field and CP content of silage, without affecting the fermentation process, even when the corn ears were removed before ensiling.