Golfdom, December 2011

T H E P R O M I S E O F C O M P O S T I N G FIGURE 1 ronmentally safe and agronomically advantageous soil organic amendment at acceptable costs The purpose of composting is to convert organic material that is unsuitable and incapable of being incorporated into the soil into a material that can be safely introduced into the ecosystem Successful composting is achieved from the continual supply of oxygen and water to the microbial community along with temperature and adequate mixing There is interest in the use of natural organic amendments for use on turfgrasses because of their potential effect on increasing soil microbial activity Researchers have reported significant reductions in dollar spot severity following applications of certain organic fertilizers including Milorganite Ringer Green Restore and Sustane as well as certain composts prepared from turkey litter sewage sludge and plant material A high level of microbial activity in compost is believed to be a reason composts are able to successfully suppress turfgrass diseases Increased microbial activity in soil presumably diminishes the activity of plant pathogens 30 TURFGRASS TRENDS December 2011 www turfgrasstrends com by antagonizing parasitizing or competing with pathogens Researchers from Cornell University postulated that suppression is a result of elevated microbial activity resulting in increased competition with pathogens for root exudates Studies have shown that infectious disease agents are prevented from germinating by high microbial activity in composts through competition for nutrients Through continual removal of nutrients especially carbon and iron pathogens are prevented from germinating and therefore remain inactive Disease suppression may also be due to enhanced microbial breakdown resulting in an increased availability of nutrients which may stimulate plant recovery from disease infection Known bacterial b and fungal f species in compost include Fusarium heterosporum f Acremonium spp b Rhizoctonia spp f Enterobacteria cloacae b Pseudomonas fluorescens b and Pseudomonas lindbergii b all of which have been shown to suppress dollar spot Continued from page 29 Naturally suppressive composts can be incorporated into normal turfgrass maintenance PHOTO COURTESY CLINT WALTZ PH D