ISHS Acta Horticulturae 469: International Symposium on Composting & Use of Composted Material in Horticulture
NITROGEN AVAILABILITY FROM COMPOSTS AND BLENDS OF COMPOSTS AND FERTILIZERS |
| Author: | L. J. Sikora |
| Keywords: | fertilizer equivalents, N mineralization rate, blends |
| Abstract:
A study was conducted to compare the nitrogen (N) availability of blends of biosolids compost or municipal refuse-biosolids cocompost with urea(U) or NH4NO3(N) fertilizers to fertilizer alone on growth and N uptake of tall fescue (Festuca arundinacea L.). Blends which provided 0, 16.7, 33 or 50 % of the N kg-1 application rate as compost N and 100, 83.3, 67 or 50% as fertilizer N were added to Sassafras soil (Typic Hapludults). Study 1 had a 150 mg N kg-1 application rate and study 2 had 120 mg N kg-1. Compost N mineralization was assumed to be 10% and comparisons were made on a fertilizer N equivalency basis. Yield and N uptake from blends of biosolids compost or municipal refuse-biosolids co-compost and NH4NO3 were not different from the equivalent NH4NO3 treatment. In study 2 which compared blends of biosolids compost and either urea (U) or NH4NO3(N) to fertilizer alone, yield and N uptake were not different from the equivalent fertilizer treatment with one exception. Yield and N uptake from 50% NH4NO3 -50% biosolids compost blend were greater than the equivalent 66 mg NH4NO3-N kg-1 treatment. Compost fertilizer equivalent based on a 10% organic nitrogen mineralization rate was accurate in blends with fertilizer. Greater yield and N uptake than predicted were seen when NH4NO3 content in the fertilizer compost blend was below 88 mg N kg-1 and did not mask the additional benefit of compost amendment. When an approximate N mineralization rate for compost is known, it is possible to formulate blends with fertilizer that will predictably support crop growth. | |
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