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item Douds, David
item Nagahashi, Gerald
item Reider, C
item Hepperly, Paul

Submitted to: Biological Agriculture and Horticulture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2007
Publication Date: 10/1/2007
Citation: Douds, D.D., Nagahashi, G., Reider, C., Hepperly, P. 2007. Inoculation with am fungi increases the yield of potatoes in a high p soil. Biological Agriculture and Horticulture. 25:67-78.

Interpretive Summary: Arbuscular mycorrhizal [AM] fungi are beneficial soil fungi that colonize the roots of most crop plants and aid in absorbing nutrients from the soil. Utilization of these fungi may help farmers decrease the application of chemical fertilizers and increase their yields. We have developed a system that allows farmers to grow these fungi on their farms in a mixture of compost and vermiculite. Here, we tested the ability of fungi produced by this system (“inoculum”) to influence the growth and yield of potato at the experimental farm of The Rodale Institute. A small amount of this inoculum, a commercially available form of AM fungi, or a compost and vermiculite mixture without AM fungi was placed in the soil directly below seed potatoes. In the first year (2002), inoculation with AM fungi increased the harvest of potatoes by 33-45% relative to plants that received no AM fungi. The yield difference was lower in 2003; 10-20% increase over uninoculated plants. These results demonstrate the potential economic benefit to farmers from utilization of AM fungi that they can produce themselves on their farms.

Technical Abstract: Arbuscular mycorrhizal (AM) fungi are potentially an important tool in agricultural systems which reduce or eliminate chemical inputs common in modern agriculture. We tested the response of potato (Solanum tuberosum L. cv Superior) to inoculation with AM fungus inocula in a field with very high available P (375 µg g-1 soil) in two growing seasons. Inoculation treatments included a commercially available inoculum containing Glomus intraradices, inocula produced on-farm in compost and vermiculite mixtures, and a control treatment consisting of a fresh compost and vermiculite mixture. In addition, two farming systems were imposed: conventional chemical fertilizers or dairy manure composted with leaves were applied to meet recommended nutrient requirements. Yields of tubers in the first year were significantly increased by AM fungus inoculum 33% under conventional fertilizer application and 45% with compost addition vs. controls of each system. The response to inoculation the second year was less, however yields of inoculated plants were 10 to 20% greater than controls. There was a significant positive treatment effect of inoculation upon production of larger sized potatoes in the second year. Neither year saw a marked difference in yield response among AM fungus inocula. These results demonstrate the potential yield benefits of inoculation of potatoes with AM fungi produced on the farm.