The manure managed and spread correctly allow for optimal used of the fertilizer elements without any harm to the environment. Part of this management is the evaluation of the nitrogen content of the manure in order to determine the optimal application rate. Laboratory testing can be realized in advance, however even if the manure is well mixed the homogeneity of the nutrients content can differ from one load to subsequent ones. The determination of the nitrogen content just before spreading would improve the nutrient management and optimize the fertilizing value of the manure and would also improve the confidence producers have in the valorization of manure they spread on their lands. The soil hygrometer has been used to estimate different constituent in manure. However this method gives poor estimates for ammoniacal nitrogen (NH4). A nitrogen measurer AGROS has been developed in Sweden. AGROS has been tested on site and compared with the soil hygrometer and standard laboratory testing. For swine manure, AGROS has been very reliable in evaluating the NH4 content, as good as laboratory testing and superior to the hygrometer technique. A relationship established with laboratory tests can be made to estimate the total nitrogen content of the manure. The cost of an analysis with this measurer is evaluated at $2,00 to $4,50 compared to $25,00 for laboratory testing. No calibration is necessary and the reading of the NH4 content is direct.

Direct measures of the nitrogen content in the manure could help adjust the application rate when spreading or in case the nitrogen is not the limiting nutrients in the manure, this result would help in the determination of the mineral nitrogen needed to assure an optimal fertilization.