Leaf Removal Influences Grain Yield of Diverse Pulse Crops.

Most of the world’s hungry people live in developing countries where they are subject to food insecurity and malnutrition. As communities strive to intensify agriculture and produce more to meet their needs, questions remain as to whether what is currently produced is well utilized. Utilization of legume leaves for human food as leafy vegetables or forage presents an opportunity to use leaves that may otherwise be unused. We conducted a field study in central Iowa to determine nutrient concentrations in leaves of soybean (Glycine max), cowpea (Vigna unguiculata), and lablab (Lablab purpureus) harvested at six-leaf stage and the influence of leaf harvest on subsequent grain yield.  For each entry, 0, 33, 66, or 99% of leaves were harvested.   Dry pulse leaves had considerable amounts of nutrients. Mean concentration of crude protein in dry leaves for 2013 and 2014 was 229 mg kg^-1, 17,832 mg kg^-1 for calcium, 4,461 mg kg^-1 for Mg, 21,991 mg kg^-1 for K, 3,702 mg kg^-1 for P, 113 mg kg^-1 for Mn, 205 mg kg^-1 for Fe, 13 mg kg^-1 for Cu, 86 mg kg^-1 for Zn and 2806 mg kg^-1 for S.  In 2013, leaf harvest did not significantly impact grain yield at the end of the season in soybean, cowpeas and lablab. Unlike 2013, leafing percentage had significant impact on 2014 yield; the control had 20, 32, and 35% more yield than plots at 33, 66 and 99% defoliation. Additional research is required to determine the influence of leaf removal from pulses grown on soils with lower fertility levels than those in central Iowa.