The interaction between nitrogen and water in The growth of Grass Swards: I. Methods and dry matter results

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Abstract
Summary: An experiment examined the interaction between nitrogen and irrigation on a sward of Lolium multiflorum (Italian ryegrass). Between rates of 100 and 200 units of nitrogen per acre, the response to nitrogen over the whole season was not increased by irrigation. Positive and negative interactions occurring in different periods cancelled each other out. Between rates of 200 and 400 units of nitrogen per acre, irrigation substantially increased the response to nitrogen, negative interactions being small relative to positive interactions. The results suggest that the moisture status of the upper few inches of the soil is an important factor in determining response to applied nitrogen. Response to nitrogen was increased when irrigation improved the moisture status of this zone.
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