Barley response to nitrogen and non-nutritional benefits of legume green manure |
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Authors: | H H Janzen G B Schaalje |
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Institution: | (1) Agriculture Canada Research Station, T1J 4B1 Lethbridge, Alberta, Canada |
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Abstract: | Green manure application may benefit subsequent crops not only by improving nitrogen (N) fertility but also via non-nutritional
mechanisms. The quantification of the latter effect, however, is complicated by the confounding effect of N fertility. Two
experiments were conducted in controlled environments to partition the yield response of barley to green manure between N
and non-nutritional effects. Each experiment included a factorial of fertilizer N application rates and green manure application
rates. The fertilizer was labelled with 15N to facilitate discrimination between N sources. Approximately 24% of the N applied in green manure was assimilated by barley
after 45 days (Experiment 1) and 32% was recovered by barley grown to maturity (Experiment 2). Apparent recovery of green
manure-N by barley was not appreciably affected by fertilizer application. Regression analysis of the relationship between
dry matter yield and plant N uptake demonstrated that yield responses to green manure application were not entirely attributable
to improved N fertility. For a given amount of N assimilated by the crop, yields were higher in green manure-amended treatments
than in those receiving no green manure. In barley grown to maturity, barley response to N and non-nutritional effects were
estimated to be 5.3 and 2.2g pot−1, respectively. The relationship between dry matter yield and N uptake is suggested as a method for distinguishing nutritional
and non-nutritional yield responses. This approach assumes that no other nutrient is limiting growth. The presence of non-nutritional
benefits observed in this study demonstrates that the agronomic value of green manure is not limited to N release and casts
doubt on the assumptions inherent to calculation of fertilizer equivalents.
Contribution 3879132
Contribution 3879132 |
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Keywords: | barley fertilizer green manure legume lentil nitrogen non-nutritional response |
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