Evaluation of fertigation applied to furrow and overhead irrigated cotton grown in a Black Vertosol in Southern Queensland, Australia

Antille, D. L. (2018) Evaluation of fertigation applied to furrow and overhead irrigated cotton grown in a Black Vertosol in Southern Queensland, Australia. Applied Engineering in Agriculture, 34 (1). ISSN 0883-8542

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Abstract

Field trials were conducted at gated pipe surface and overhead irrigation sites established to cotton (Gossypium hirsutum L.) to evaluate irrigation and fertigation management using a model-based control system. The control strategies determined the timing and volume of irrigation, and the rate of fertilizer-N to apply through fertigation. For this, nitrogen (N) was applied in-crop season using urea ammonium nitrate (UAN, 30% N solution) at a rate of 40 kg ha-1 N. At the furrows site, the uniformity of distribution of fertilizer-N applied through fertigation was satisfactory, which was achieved both at distance (600 m) and depth (0-600 mm). Applying fertilizer-N through fertigation, at the rate used in this study, showed relatively small (≤8%) improvements in cotton yield, which was explained by relatively high N rates (180 kg ha-1 N) applied before planting. Given current price ratios (fertilizer-to-cotton), application of N through fertigation appears to be economical in both systems, but relative agronomic efficiencies and economic return from the fertilizer applied were lower in furrow compared with overhead (P<0.05). Fertigation may be recommended when pre-season N application rates are low (e.g., <100 kg ha-1 N), particularly in overhead irrigation as significantly higher efficiencies both in terms of water and N use can be achieved with this system. This would enable some of the operational constraints associated with application of N in-crop season to be overcome; thereby, reducing the need for high rates of N applied up-front. For the overhead system, there were also advantages compared with the furrow system in terms of reduced potential for N2O emissions after irrigation or fertigation. Overall, short-term (30-day period) soil emissions of N2O were approximately eight times higher in furrow compared with overhead. Emissions from non-fertigated crops were approximately two times higher in furrow compared with overhead. Emissions from the fertigated crop under the overhead system were comparable to the non-fertigated crop of the furrow system (P>0.05). In both systems, fluxes were highest within five days of irrigation or fertigation, but they decreased significantly after that time as soil moisture content (water-filled pore space) and soil nitrate levels decreased due to crop uptake. Nitrous oxide fluxes were similar in furrow and overhead 15 days after the irrigation or fertigation event. Areas that warrant further investigation are presented and discussed, including the need for improved timing of fertilizer delivery during the irrigation cycle to ensure that N losses through leaching or gaseous evolution (e.g., N2O, N2) are not economically or environmentally significant.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Access to ArticleFirst version in accordance with the copyright policy of the publisher.
Faculty / Department / School: No Faculty
Date Deposited: 09 Feb 2018 00:15
Last Modified: 09 Feb 2018 05:14
Uncontrolled Keywords: greenhouse gas emissions, irrigated cotton, nitrogen use efficiency, urea ammonium nitrate, water-run urea
Fields of Research : 07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070306 Crop and Pasture Nutrition
05 Environmental Sciences > 0503 Soil Sciences > 050301 Carbon Sequestration Science
07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079902 Fertilisers and Agrochemicals (incl. Application)
09 Engineering > 0999 Other Engineering > 099901 Agricultural Engineering
07 Agricultural and Veterinary Sciences > 0799 Other Agricultural and Veterinary Sciences > 079901 Agricultural Hydrology (Drainage, Flooding, Irrigation, Quality, etc.)
Socio-Economic Objective: D Environment > 96 Environment > 9609 Land and Water Management > 960904 Farmland, Arable Cropland and Permanent Cropland Land Management
Identification Number or DOI: doi:10.13031/aea.12519
URI: http://eprints.usq.edu.au/id/eprint/33545

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