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ARS Home » Research » Publications at this Location » Publication #185983
Title: ORGANIC AMENDMENTS TO IMPROVE SOIL PRODUCTIVITY AND NUTRIENT CYCLING

Author
item PARAMASIVAM, S - SAVANNAH STATE UNIV
item SAJWAN, K - SAVANNAH STATE UNIV
item ALVA, ASHOK

Submitted to: Plant Nutrition Colloquium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2005
Publication Date: 9/1/2005
Citation: Paramasivam, S., Sajwan, K.S., Alva, A.K. 2005. Organic amendments to improve soil productivity and nutrient cycling. 15th International Plant Nutrition Colloquium Proceedings, Beijing, China, Sept 14-19, 2005, p. 1090-1091. (And on CD).

Interpretive Summary: Soil amendments are used to improve the soil quality and nutrient availability in an effort to enhance plant growth and production. Coal combustion byproducts (CCBP) and sewage sludge (SS) have been used as soil amendments depending on the source of each available in proximity to the agricultural land. Due to the contrasting characteristics of each of the above products and differences in nutrient elements combining the above two sources provide a source of most nutrients and minimize the drastic changes in soil pH unlike application of each of the above sources as sole amendment. However, depending on the source of origin of the above byproducts, there could be some concern in terms of high levels of heavy metals which could be harmful to the plants. In this study the growth and nutrient composition of collard greens grown on two soils amended with different rates of fly ash (FA) and SS mixture (0, 24.7, 49.4, 98.8, or 148.2 tonnes per hectare) were examined. The regression analysis showed that dry matter production of collard greens in both soils peaked at about 80 tonnes per hectare rate of FA:SS mixture amendment. Overall, the accumulation of Cd, Cr, and Pb in the above ground portion of the plants increased at 49.4 tonnes per hectare rate of FA:SS amendment. Therefore in the interest of keeping the levels of the above heavy metals at minimum, it is advisable to practice low-loading rates of FA:SS mixture for growing leafy vegetables.

Technical Abstract: A sandy soil from Florida (Candler fine sand, pH = 6.8) and a loamy sand from Georgia (Ogeechee loamy sand, pH = 5.2) were amended with either domestic or industrial origin sewage sludge (DSS or ISS) and fly ash (FA) mixture (1:1) at either 0, 24.7, 49.4, 98.8, or 148.2 Mg/ha and incubated at field capacity moisture content for six months prior to planting collard greens (Brassica oleracea var. acephala) to study the improvement in soil productivity and nutrient supply for vegetable crops. Seven seedlings were grown for 6 weeks and dry matter yield and elemental concentrations were measured in the above and below ground parts. The dry matter yield increased with increasing rates of amendments up to 80.0 Mg/ha and then decreased at higher rates of amendments. A similar trend was observed for Ca, Mg, and P concentrations in below ground plant parts. However, the concentrations of these elements in above ground plant parts increased with increasing rates of amendments. Concentrations of Cu, Zn, Mn, and Fe increased with increasing amendment application rates up to 98.8 Mg/ha irrespective of plant parts. Accumulation of selected heavy metals (Cd, Cr, Pb) and their distribution in above ground parts increased at 49.4 Mg/ha application rate. This is an important consideration in using these amendments for leafy vegetables such as collard greens.