Changes in Soil N pools and Microbial Activity Following Additions of Organic Amendments and Fertilizer Formulations: Organic production systems have been shown to modify the turnover of C and the formation of soil organic matter and stimulate nutrient cycling through enhancement of the soil microflora. The current ARS field trials involves the analyses of soil organic C, N, microbial characteristics and selected soil physical and crop quality measurements. The objectives of this study are to 1) evaluate the uptake of N by potato from a variety of organic sources and fertilizer formulations and 2) Quantify key soil agroecological processes (carbon and nitrogen cycling)
and application rates of organic amendments that
optimize physiological development (nitrogen capture,
plant growth rate) of potato under irrigated organic
Effect of Foliar Applied Plant Elicitors on Microbial and Nematode Populations in the Potato Root Zone:Foliar applications of benzo (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester (BTH) and the microbial protein, harpin reduced the nematode infection index of lesion and root knot nematodes but had no harmful effects on other soil organisms.
Yield Effects of Potato Common Scab (Streptomyces scabies)from Manure Applications.
The potential for utilizing dairy manure as a fertilizer
by reducing potential pathogen issues could create a significant market for dairy manure that could facilitate the export of nutrients off regional dairies and reduce purchased, fertilizer inputs for potato production. We demonstrated that the application of anaerobic
digested manure in absence of the pathogen reduced tuber yield 12%. Tuber yields of two potato cultivars
(Chieftain, Cal white) when grown with Streptomyces scabies decreased 15% to 32% depending on potato cultivar under low and high levels of the pathogen, respectively. The scab pathogen was shown to exert significant negative impacts on potato other than the formation of lesions that are unreported losses in production.