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

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.

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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.

Item Type: Conference or Workshop Item (Paper)
Subjects: Mandate crops > Sorghum
Others > Watershed Management
Others > Agriculture-Farming, Production, Technology, Economics
Others > Fertilizer Applications
Depositing User: Mr Sanat Kumar Behera
Date Deposited: 07 Mar 2012 09:14
Last Modified: 07 Mar 2012 09:14
URI: http://oar.icrisat.org/id/eprint/5686
Acknowledgement: UNSPECIFIED
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