The 3,4-dimethyilpyirazole phosphate (DMPP), commercialized as Entec, is a nitrification inhibitor developed by BASF (Germany) that may help to minimize N losses and to obtain a higher profit from N fertilizers. A two-year field trial was established in 2001 in the Northeast of Spain to assess the effects of DMPP on N use efficiency (NUE) and to determine the economic returns. Seven treatments have been carried out comparing the effect of DMPP on pig slurry and on mineral fertilizers. The application of DMPP resulted in better efficiency indexes on mineral fertilizers. An apparent nitrogen recovery of 0.465 kg kg-1, on average, was obtained for the Entec treatment. A net benefit of € 809 ha-1, on average, was obtained for the Entec treatment compared with € 607 ha-1 for the control treatment. The results of this study suggest that the nitrification inhibitor could improve farmer profit in irrigated wheat on a calcareous soil.

Pig slurry is a valuable nutrient resource but constitutes a waste disposal problem in areas of high animal density. In the semiarid area of Pla d'Urgell, in the Ebro Valley, North-East Spain, irrigated crops receive large amounts of nutrients in the form of manure and mineral fertilizers. We studied the effect of pig slurry and additional side-dress mineral fertilizers on irrigated wheat, Triticum aestivum L., on a coarse loam soil, with high soil P and K levels. Yields increased by 62.3% when using pig slurry. The application of ammonium sulfate nitrate sidedress did not significantly increase wheat production. The average apparent recoveries were higher for potassium (88.7%) than for nitrogen (51.3%) and phosphorus (36.3%). Greater amounts of soil NO 3 -N were measured over the four growing seasons, which was consistent with the amount of N applied. Macronutrient and micronutrient uptake was significant higher for pig slurry treatments, but only small differences were found between the pig slurry and pig slurry plus ammonium sulfate nitrate treatments. The unfertilized treatment showed significantly lower soil P, K, Cu and Zn content than pig slurry treatments; 34%, 21%, 34%, and 26% respectively. These findings could be used to develop a nutrient management plan based on knowledge of soil test results and crop nutrient removal. This could help to improve the use of pig slurry and mineral fertilizers on limited available land areas and prevent the accumulation of potentially toxic elements in soils and the export of nutrients through agricultural drainage. over-fertilized soils / irrigated wheat / nutrient uptake / nutrient recovery / pig slurry * Corresponding author: jmvillar@macs.udl.es Article published by EDP Sciences and available at

This paper reports a 406 day outdoor experiment (performed in pots) to determine the influence of the new nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), when added to pig slurry (PS), on the growth and chemical composition of ryegrass. Pots containing a loamy, calcareous soil were treated with either no PS or 73.7, 147.3 or 221 cubic cm pot-1, with or without DMPP, prior to seeding with ryegrass. The greatest quantity of above ground dry matter was obtained with the highest dose of PS + DMPP (36.3 g pot-1) – 7.4% greater than that obtained for the same treatment without DMPP, and 46.1% greater than with the no PS treatment. The plants treated with the high and medium doses of PS + DMPP absorbed 70% of total N during the first quarter of the experimental season (104 days). Without DMPP, N uptakes were 55.7% and 63% for the high and medium treatments respectively. The inhibition of nitrification with DMPP increased agronomic efficiency and reduced N leaching by 17%.