LSU Historical Dissertations and Theses

1996

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Sam E. Feagley

Wayne H. Hudnall

Abstract

Application of composted municipal waste to agricultural lands has potential benefits to improve soil fertility and crop yield. It may lead to accumulation of heavy metals within soils and leaching of nutrients and heavy metals into the ground water. The objectives of this study were to investigate: (1) the effects of composted municipal waste and fertilizer on soil chemical properties and sugarcane elemental uptake and yield; and (2) the leachability of elements in compost amended soils. Results of three field experiments from a Baldwin silty clay loam and a Memphis silt loam showed that compost application at $\ge$33.6 Mg/ha increased soil nutrients, organic matter, and pH. Compost application also increased the Cu, Zn, Cd, and Pb for the Baldwin soil and Cu for the Memphis soil. The increased metal concentrations were much lower than toxic levels. Plant tissue and sugar juice data demonstrated that compost was beneficial for sugarcane growth and there was no heavy metal accumulation. Yield data indicate that compost application at $\ge$134.4 Mg/ha can produce plant cane and sugar yields equivalent to those obtained by applying inorganic fertilizer (179 kg N, 101 kg $\rm P\sb2O\sb5$, 134 kg K$\sb2$O, and 27 kg S per hectare) on a Baldwin soil. The correlation analysis between extracted trace metals in soils and plant tissue digests showed that the increased heavy metals did not reflect the amounts taken up by sugarcane. This indicates that the DTPA method of soil metal extraction is a questionable index for the bioavailability of trace metals in compost amended soils. Leaching experiments using soil columns showed that nutrient and heavy metal concentrations in leachate increased with increasing compost rate, but decreased with time. Concentrations of NO$\sb3$-N, SO$\sb4$-S, and Cl$\sp-$ were higher than the primary or secondary drinking water standards during the first 2 wk. But, heavy metals concentrations were lower than the primary or secondary drinking water standards throughout the leaching period except for Mn. These results suggest that there is a potential contamination of groundwater with the nutrients following compost application, but contamination of groundwater with heavy metals should be negligible.

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