Agronomics of land application of municipal collected shade tree leaves: II. Soybean and corn production

Land application of municipal collected shade tree (MCST)-leaves may impact crop production as a result of changes in soil conditions and supply of plant nutrients. The high C-to-N ratio of MCST-leaves causes immobilization of soil mineral N and may increase the need for supplemental N fertilizer. This study, conducted near Pitstown, NJ on Quakertown silt loam (fine-loamy-mixed, mesic, Typic hapludult) from 1991 to 1994, examined the effect of application rate of MCST-leaves on soybean nodulation, plant tissue nutrient concentrations and fertilizer N needs of soybean and corn. Each November from 1990 to 1992, MCST-leaves were applied at 0, 22.5 and 45 Mg ha^-1 yr^-1 to the same set of plots cropped to either continuous soybean, continuous corn, a soybean-corn-soybean rotation, or a corn-soybean-corn rotation. Plots cropped to soybean were split to receive either 0 or 112 kg N ha^-1, and plots cropped to corn were split to receive either 156 or 268 kg N ha^-1. Crop rotation system generally did not influence soybean or corn yield or tissue nutrient concentration. Soybean nodulation was enhanced when grown on soil amended with MCST-leaves. Soybean and corn grain yields on soil amended with MCST-leaves were generally comparable or better than yields on unamended soils. Supplemental N fertilizer was not necessary for increasing soybean yields on soil amended with MCST-leaves comparable to unamended soil. Comparable corn grain yields were produced on amended soil with the same rate of N as the usual practice for unamended soil. Plant tissue analysis indicated that applying more N fertilizer than the usual practice to soybean or corn was not necessary to counteract soil N immobilization and crop N deficiencies expected to result from the application of MCST-leaves to soil. Plant analysis also revealed that application of MCST-leaves often increased the Ca concentration in soybean and corn leaf tissue.