YIELD AND QUALITY OF ANNUAL CROPS SEEDED FOLLOWING PEA HARVEST

Abstract

Pea (Pisum sativum L.) are grown for canning and freezing on over 40 000 ha (1979–1982 average) in Wisconsin and substantial acreages are also seeded to other canning crops. The majority of this land remains idle after harvest in late June or early July. Crops could be seeded on this land to be used as forage for livestock or for energy conversion. The objective of this study was to evaluate the yield and forage quality of several summer annual crops seeded after pea harvest. Field experiments were conducted during 1980 and 1981 on a Piano silt loam soil (Typic Argiudoll) at Arlington, Wisconsin. ’Alaska’ pea were planted in late April and harvested in late June. After pea harvest, plots were cultivated to prepare a seedbed for the second crops, which were planted in late June. The second crops included three sorghum (Sorghum bicolor (L.) Moench) cultivars, soybean (Glycine max L.), normal and male-sterile early maturity (RM 95) corn (Zea mays L.), and two mixed cropping systems. Mixed crops were male-sterile corn grown with either soybean or field bean (Phaseolus vulgaris L.). Second crops were harvested late in September. Male-sterile corn had the highest 2-yr average yield of DM at 9.8 Mg∙ha−1 and sweet sorghum had the second highest yield even though it was reseeded 13 days later in 1981 due to poor germination. The normal corn average yield was only 0.5 Mg∙ha−1 less than that of sweet sorghum and should be considered a viable option as a second crop after canning pea harvest. Soybean would not be recommended for this use because its yield was considerably below that of any other crop in both years. Soybean forage was highest in N and lowest in NDF. Of the grass crops the highest IVDMD values were for normal corn (64.2%), male-sterile corn (63.7%), and sweet sorghum (64.9%). Sorghum-sudangrass was lowest in IVDMD in 1980 (53.0%) and in 1981 (60.1%). Sweet sorghum and the two corn types were lower in neutral detergent fiber, acid detergent fiber and acid detergent lignin than sorghum-sudangrass. Considering both yield of DM and the quality of the forage produced, male-sterile corn, sweet sorghum and normal corn can be identified as the superior crops for planting after pea harvest. Mixed cropping male-sterile corn with soybean or field bean gave no advantage in yield or quality.Key words: Corn, sorghum, pea, IVDMD, NDF, N