Effects of Growth Medium and Fertilizer Rate on the Yield Response of Soybeans Exposed to Chronic Doses of Ozone

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Abstract
A study was made to determine whether wide variation in fertilizer rates or type of growth medium would affect the response of soybeans, G. max ''Davis'', exposed to chronic doses of ozone (O3) in open-top field chambers. Responses to O3 were compared from plants grown in the ground or in pots containing an artificial growth medium. In 1977, the yield of plants grown in pots containing soil, sand, and a mixture of perlite, peat moss and vermiculite was greater than that of plants grown in the ground; in 1978, the reverse was true. However, the percentage yield loss caused by O3 was not affected by the growth medium either year. Separate tests were made for potted plants that received different levels of fertilizer. At moderate fertilizer rates, the yield response to different doses of O3 was not significantly affected by fertilizer rate for either year. In 1978, plants with no fertilizer added were severely stunted and even relatively high doses of O3 did not further decrease yield. Plant response to O3 apparently will be fairly uniform over a range of substrate types and fertilizer rates when edaphic conditions are adequate to insure normal plant growth.