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Effect of fertiliser nitrogen and irrigation on root growth and extension, and water uptake of post-rainy season sorghum

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Relation http://oar.icrisat.org/5686/
 
Title Effect of fertiliser nitrogen and irrigation on root growth and extension, and water uptake of post-rainy season sorghum
 
Creator Lee, K K
Singh, P
Wani, S P
Rego, T J
Trimurtulu, N
Monteith, J L
 
Subject Sorghum
Watershed management
Agriculture-Farming, Production, Technology, Economics
Fertilizer Appications
 
Description Effects of fertilizer nitrogen (N) and irrigation on root development are discussed by collating the
observations in published reports with those in our study using field-grown sorghum [Sorghum
biocolor (L.) Moench] on a deep Vertisol in semi-arid tropical India. In our study, the total root
biomass was affected by fertilizer-N and irrigation and by their interaction. It is the top soil layers
that contribute largely to increased root biomass due to fertilizer-N and irrigation. These
observations agree with those in other reports. The total root length was not significantly affected by
fertilizer-N, but was consistently higher under dry conditions than under irrigated conditions.
Spatial distribution of root length did not fit a simple mathematical model such as linear, exponential
or logistic curve, except at very young growth stages under irrigated conditions. Except the top 16-
cm layer, the depth at which root length density zvas maximum shifted to deeper layers as sorghum
grew. This may indicate that some roots die after water extraction and that new roots grow at the soil
layers where water zvas available. This specific feature would contribute to the complexity of
modeling of root development. Rooting depth was not affected by fertilizer-N, but it was consistently
greater under dry conditions than under irrigated conditions. The root depth had a linear
relationship with time under dry and irrigated conditions up to the physiological maturity stage.
Water uptake by sorghum was determined as the difference between measured evapotranspiration
and estimated soil evaporation. In non-irrigated treatment, the differences in water uptake among N
treatments were not significant. In the irrigated treatment, the rates of 30 to 150 kg N ha (30 N
and 150 N, respectively) resulted in significantly higher water uptake than no fertilizer-N. The
fertilizer-N effect in our study zvas not as clear-cut as that in other reports.
 
Date 1996
 
Type Conference or Workshop Item
PeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://oar.icrisat.org/5686/1/effect_of_Nitrogen_279-289_1996.pdf
Lee, K K and Singh, P and Wani, S P and Rego, T J and Trimurtulu, N and Monteith, J L (1996) Effect of fertiliser nitrogen and irrigation on root growth and extension, and water uptake of post-rainy season sorghum. In: Proceedings of the International Workshop: Dynamics of Roots and Nitrogen in Cropping Systems of the Semi-Arid Tropics, 21-25 November 1994, ICRISAT Patancheru, Andhra Pradesh, India.