Efficacy of Supplemental Irrigation and Nitrogen Management on Enhancing Nitrogen Availability and Urease Activity in Soils with Sorghum Production

Gilbert C. Sigua, Kenneth C. Stone, Phil J. Bauer and Ariel A. Szogi
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Gilbert C. Sigua: United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC 29501, USA
Kenneth C. Stone: United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC 29501, USA
Phil J. Bauer: Retired Agronomist, USDA-ARS, Florence, SC 29501, USA
Ariel A. Szogi: United States Department of Agriculture, Agricultural Research Service, Coastal Plains Soil, Water, and Plant Research Center, Florence, SC 29501, USA

Sustainability, 2020, vol. 12, issue 20, 1-15

Abstract: The soil nitrogen (N) availability and urease activity (UA) in a humid ecosystem with variable rainfall distribution and poor soil fertility are not well understood. A complete appreciation of N cycling in the soil–water–plant continuum is needed to better manage N and water in regions that will be strongly affected by climate change. A sorghum ( Sorghum bicolor L.) study located in Florence, South Carolina, USA, was conducted using a variable-rate pivot system. We hypothesized that supplemental irrigation (SI) and N would enhance UA and N uptake while minimizing the concentration of N in porewater (TINW). The aim of the study was to assess the impact of SI (0, 50, and 100%) and N fertilization (0, 85, and 170 kg N ha −1 ) on: UA; total N (TNS); total inorganic N (TINS); TINW; and N uptake of sorghum. Results support our research hypothesis. The greatest UA was from 0% SI and 170 kg ha −1 (18.7 µg N g −1 ha −1 ). Porewater N (mg L −1 ), when averaged across SI and N showed a significantly lower concentration at lower soil depth (9.9 ± 0.7) than the upper depth (26.1 ± 2.4). The 100% SI had the greatest biomass N uptake (NUPB) of 67.9 ± 31.1 kg ha −1 and grain N uptake (NUG) of 52.7 ± 20.5 kg ha −1 . The greatest NUPB (70.9 ± 30.3 kg ha −1 ) and NUG (55.3 ± 16.5 kg ha −1 ) was from the application of 170 kg N ha −1 . Overall, results showed that proper use of water and N enhanced soil N dynamics, and improved biomass productivity and N uptake of sorghum.

Keywords: Coastal Plain region; urease activity; nitrogen uptake; supplemental irrigation; sorghum; total nitrogen; pore water; Norfolk; sorghum; climate change (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
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