Assessing the efficiency of nitrogen application is a valuable first step in establishing an optimum N fertilizer management plan. The aim of this study was to elaborate a sustainable N management system for sown grassland installed in temperate regions, through manipulation of nitrogen use efficiency and nitrogen response efficiency (NRE) indicators. Research was performed in western Romania. The biological material consists in two forage species of major importance for the forage base worldwide, namely Trifolium pratense L. and Lolium multiflorum Lam., in pure stands and in mixture. Both forage species were sown at two different spacings between rows (12.5 and 25.0 cm) and were fertilized with nitrogen (N) in three doses (N0-control, N50-fertilized with 50 kg N ha−1 and N100-fertilized with 100 kg N ha−1). The studies were made in 2016 and 2017, years very different from each other in matter of rainfalls. The results revealed a different behavior of the three sward types analyzed: while in Trifolium pratense monoculture and in the mixture of the two species studied, less N was removed than was applied; on the other hand Lolium multiflorum monoculture used a high proportion of the N applied, being at the limit to access N from the organic pool or residual N from fertilizer applications to a preceding crop.

The effect of different technological conditions on forage yield, growth behavior and competition ability of ryegrass, red clover and their mixture was analyzed. The results showed that red clover makes better use of the nutrition space in the case of variants sown in mixture with Italian ryegrass than in the monoculture, independent of the density of the plants or fertilization regime. The highest DM production was obtained at the mixture formed by red clover and Italian ryegrass on the variants sown on 12.5 cm distance between rows, the increase of the nutrition space being directly proportional to the decrease of the DM production in the case of this forage mixture.

As consequence of increasing need of higher livestock productions, in conditions of assuring environmental sustainability, comparative tests of properties of forages obtained by application of conventional technologies compared with those obtained as result of organic practices, may be useful. Thus our trial covers issues concerning comparative study of nutritional traits, expresses through chemical composition indices, of silage obtained from alfalfa resulted from two types of cultivation technologies, conventional, and organic, respectively. The experiment was carried out in a familiar farm located near Huedin, County of Cluj, Romania. Higher contents of dry matter, acid detergent fibre, and ammonia are reported in silage obtained from alfalfa cultivated in organic technology, compared to silage obtained from alfalfa conventionally produced. The ammonia content of silage obtained from alfalfa cultivated using conventional technology, reported as % from dry matter, is the single chemical index where high diversity within individual values was identified. Correlations of similar intensities were identified between the indices of the chemical composition of the silage obtained from both, conventionally and organic, cultivated alfalfa. The alfalfa cultivated in organic system promotes higher amounts of crude protein, neutral detergent fibre, and total volatile fatty acids, in alfalfa silage.

Mineral and organic fertilization have a huge effect on natural grasslands. The purpose of this research is to assess the state of the biodiversity and pastoral value for grasslands from the Transylvanian Plateau area. In this area has been analyzed the floristic composition and a series of ecological indexes, respectively humidity, soil reaction, temperature and nitrogen. Other aspects taken in account were the agronomical and anthropogenic specters. The analyzed grasslands are placed in the perimeter of Gheorgheni village, from Cluj County. Experience includes 20 experimental variants with organic fertilization with combined with mineral fertilization, 5 variants in 4 rehearsals. Each experimental variant is 2 m long X 5 m wide. In most hill meadows the economic efficiency is relatively low, and in order to be increased, it is necessary to apply the whole complex of measures for their improvement, care and exploitation, of which a special role is the application of appropriate treatments that stimulate the development of valuable species. Several researches show that applying fertilizers on grasslands is economically justified since, generally, 1 kg of active element results in an increase of 80-100 kg of green matter.