Sprinkler Irrigation Is Effective in Reducing Nitrous Oxide Emissions from a Potato Field in an Arid Region: A Two-Year Field Experiment

In arid and semi-arid regions, water-saving irrigation is the primary mode of local agricultural production. Since the chemical fertilizer is the principal source of nitrous oxide (N2O) emissions, we present results from a two-year (2016–2017) field experiment on a potato field to verify the general influence of water-saving irrigation on N2O emissions. A split-plot experiment was established with two irrigation systems and two fertilizer treatments, which give a total of four treatments. Two different irrigation systems were investigated: (i) flood irrigation with nitrogen fertilizer (NF-FI) combined with a control without any fertilizer (C-FI) and (ii) overhead sprinkler irrigation with a nitrogen fertilizer (NF-SI) accompanied with a control without any fertilizer (C-SI). The N2O emissions of the fertilizer treatment were greater than those of the control under each irrigation system. In plots where the fertilizers were applied, using overhead sprinkler irrigation reduced the average cumulative N2O emissions between 40.72% and 59.65% compared with flood irrigation. This was mainly due to the lower amount of water applied and the lower availability of NO3−-N and NH4+-N of soil associated with an overhead sprinkler irrigation. This work shows that the overhead sprinkler irrigation is an effective strategy to use to save water and mitigate emissions of the atmospheric pollutants N2O in comparison to flood irrigation.

Assessment of the CROPWAT 8.0 software reliability for evapotranspiration and crop water requirements calculations

The results of the study devoted to assessment of accuracy and reliability of the CROPWAT 8.0 software application calculations of the evapotranspiration and crop water requirements are represented in the article.The study was based on the results of the perennial field experiments, conducted during the period from 2012 to 2017 at the irrigated lands of the South of Ukraine with different crops, namely: sweet corn, grain corn, soybean, sorghum. We assessed accuracy of the CROPWAT 8.0 software application by the comparison of the calculated values with the real ones. We determined considerable differences between the calculated crops evapotranspiration values and crops irrigation requirements and the real ones obtained in the field experiments. The difference was the most essential in case of the drip-irrigated sweet corn crop and averaged to 46.05% for evapotranspiration and 89.20% for irrigation water requirements, correspondingly. Overhead sprinkler irrigated crops are likely to be more suitable for accurate evapotranspiration prediction by using the CROPWAT 8.0. The slightest discrepancy between the calculated and actual values of the studied parameters were determined on the overhead sprinkler irrigated grain corn crops, where the differences averaged just to 15.86% for evapotranspiration and 41.63% for irrigation norm. The results of the study gave us an opportunity to conclude that CROPWAT 8.0 software application should not be used without previous calibration and adjustment of the crop coefficients for the concrete agricultural production conditions.