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The use of nitrogen fertilizers in agriculture is currently under high pressure to reduce its environmental impact and improve its currently low efficiency. Nitrification inhibitors and/or intercrops emerged in recent decades as useful tools to combat these problems. The objective of the experiment is to study the effect of these techniques on the yield, the nitrogen use efficiency (NUE) and N leaching in a maize–wheat rotation. Six treatments were studied, combining the use of ammonium nitrate sulfate (ASN) alone or with a nitrification inhibitor (DMPSA or 3,4-dimethylpyrazole succinic acid) and the use or absence of vetch (Vicia sativa L.) as an intercrop. The results showed that fertilized treatments did not show significant differences in crop development, but the use of DMPSA delayed the nitrate (NO3−) availability and reduced N leaching losses (average N leaching reductions around 25% after maize harvest). On the other hand, the use of vetch as an intercrop helped to reduce the negative effects of N deficiency and, at the same time, increased the concentration of N in the soil during the following crop harvest (4.5 kg N ha−1 on average after wheat harvest) and reduced losses due to leaching (average N leaching reductions around 14% after the maize–wheat season). The combination of both techniques (DMPSA and vetch intercrop) at the same time presented a synergic effect and greatly improved the environmental impact of the irrigated maize–wheat system. [ABSTRACT FROM AUTHOR]

The use of urease inhibitors in irrigated systems decreases both soil ammonium (NH4+) and nitrate (NO3−) availability, and, thus, could be an easy tool to reduce N loss due to ammonia volatilization and NO3− leaching. The main goal of this experiment was to assess the effect of urease inhibitors on N use efficiency, N losses, and their economic impact in a maize-wheat field experiment. In this study, 10 treatments were compared, combining the urea fertilizer with or without urease inhibitor, applied in one or two dressings, and under optimal or sub-optimal irrigation. A single application of urease inhibitor (IN1d), coupled with the conventional urea, helped to reduce the nitrate leaching risk both during the maize period (even when compared to the two dressing treatment) and after harvest. In addition, this improvement was achieved together with an increase in economic benefit, even when compared with the application of the same amount of regular urea split into two dressings. Under low water availability systems, the benefits of applying urease inhibitors increased with respect to the application of regular urea, making this technique a very promising strategy for adaptation to climate change in arid and semiarid regions. [ABSTRACT FROM AUTHOR]