Zavala Jerez, David E.

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    Rendimiento de materia seca y caracterĆ­sticas fermentativas de ensilajes de maĆ­z ( Zea mays L.) Asociados con leguminosas anuales
    (2011) Zavala Jerez, David E.; Valencia Chin, Elide; College of Agricultural Sciences; Ramos Santana, Rafael; Randel Folling, Paul; O'Farrill Nieves, HipĆ³lito; Department of Crops and Agro-Environmental Sciences; Kolterman, Duane A.
    Corn (Zea mays L) is an ideal crop for silage due to its high levels of fermentable carbohydrates, but its major limitation for use in human and animal feeding is its low crude protein concentration (CP). An alternative to increase CP in corn silage is through its association with annual legumes, but there is little information available about the effect on dry matter yield (DMY) and fermentation characteristics. Two studies were conducted at the Experimental Substation in Isabela, PR in 2009 and 2010 on an Oxisol (Coto series) soil. The first experiment involved intercropping two annual legumes, lablab (Lablab purpureus) and sunn hemp (Crotalaria juncea), with two yellow corn varieties (HR-ORO and QPM) to assess the effect on DMY, botanical composition of forage and CP, neutral and acid detergent fiber (NDF and ADF) content, and fermentation products upon ensiling. In the second study the ears were removed or left in place before ensiling a white QPM corn intercropped or not with the above-mentioned legumes. The experimental design in the first study was a split plot and in the second it was a randomized complete blocks, both with four replicates per treatment. In each study there were two corn by three intercropped legume combination (HR-ORO and QPM, Expt.1; and QPM white with and without ears, Expt.2) in monoculture and intercropped corn-lablab and corn-crotalaria, making a total of six treatment. The corn was harvested (Expt.1) 83-d after sowing (milk stage), and the forage was ensiled in four micro-silos (15 L) per treatment. In the fresh forage DMY and botanical composition iii were determined. The micro-silos were opened after 43 days of fermentation (26Ā°C); silage samples were analyzed for DM, CP, NDF, ADF, pH and acid formed by fermentation. In Expt.1 mean weed percentage in the crop decreased from 31.0 to 13.6% (PĖ‚0.05) while DMY increased from 8,216 to 10,068 kg ha-1 when the legumes were intercropped compared with corn monoculture. The DM content of QPM and HR-ORO silages was marginally higher in their respective monocultures (27.0 and 25.1%) compared with the intercropped treatment (25.6 and 24.0%) and slightly higher with intercropped crotalaria than lablab (25.3 and 24.3%), (PĖ‚0.05). Mean CP in silages increased from 9.5% to 10.6% when legumes were intercropped compared with monoculture (PĖ‚0.05). The overall NDF of silage was 53.6% with small non-significant effects of treatment, but ADF increased from 32.7 to 37.2% when legumes were included. Overall mean values of silage composition were: pH, 3.8; lactic, acetic and total acids, 7.0, 2.5 and 9.4%; and NH3/N total, 5.6% with little effect of treatments on these variables, indicating that the silage was well preserved. In the second experiment ears with grain in milk stage were removed in three treatments, corn in monoculture (CWOE), and intercropped with lablab (CLWOE) and crotalaria (CCWOE) at 90 days and the remaining part of the plants were ensiled the following day. There were three similar treatments with ears (CE, CLE, and CCE). Ensiling procedure and silage analysis were similar to Expt.1 Among the treatments with ears DMY (kg ha-1 ) increased with intercropping from 9,890 (CE) to 11,256 (CLE) and 14,786 (CCE) with addition of legume, while among those without ears the increases were from 7,270 (CWOE) to 8,667 (CLWOE) and 10,641 (CCWOE), thus iv indicating DMY losses of 2,626, 2,584 and 4,145 as a result of ear removal, for the three respective comparisons. A greater benefit to DMY occurred when crotalaria was the intercrop (4,134) compared with lablab (1,382). Intercropping with crotalaria 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 %DM (26.6 to 25.9), but increased the %CP (10.0 to 11.9), (PĖ‚0.05). The NDF content of the silages was not affected but ADF increased from 32.9% in monoculture to 38.3% when intercropped with legume, this effect being more pronounced in the absence of ears. The results regarding pH and fermentation products were similar to those of Expt.1, except for lower acid acetic concentration, and indicated satisfactorily conserved silage. In both studies, 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.