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Our study was conducted in the framework of EFFICOND project, with the aim of evaluating the environmental effectiveness of GAEC (Good Agricultural and Environmental Conditions) standards with particular focus to the maintenance of soil organic matter (SOM) levels through the appropriate crop rotation. The study analyzed the effect of crop rotation on the build-up of soil organic matter in three different areas of Italy, located in the North (Lodi), Centre (Fagna, Firenze) and South (Foggia) of Italy, characterized by different climate, soil, and cropping systems. In the two experiments conducted in the South of Italy, in a dry Mediterranean climate, the stock of C was kept steady in most of the rotations compared with the monoculture of durum wheat. In such environment, with very dry and hot summers, introducing a year of fallow seems to improve SOM content, but these data need further investigation. In the Centre of Italy (Fagna), with less extreme climate than in Foggia, the effect of rotation compared to the monoculture of maize is negligible, but investigation on the soil organic matter composition, showed that in the rotation the SOM appeared to be more stable and, in the long term, probably more resistant to degradation. Eventually, experiments conducted in the North of Italy, showed that the monoculture, despite the application of FYM (Farm Yard Manure) or semi-liquid manure, led to a decrease of SOM. To an increase of the rotation complexity, corresponded an increase in the stock of C in soil. Summarizing, results showed that crop rotation could guarantee the maintenance of SOM level, given that the input of C to the soil is maintained at a good level or, in other word, that productivity of the system is high. Other practices such as conservation tillage, appropriate management of residues, and manure application could enhance the positive effect of rotations. Moreover, preliminary investigation of soil microbial diversity, suggests the positive effect of rotations on soil biological fertility

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An understanding of crop availability of livestock slurry nitrogen (N) is necessary to maximise crop N use efficiency and to minimise environmental losses. Results from field and laboratory incubation experiments suggest that first-year crop availability of slurry N comes mainly from its ammonium fraction because net mineralisation of organic N is often negligible in the short term. A two-year field experiment during 2011 and 2012 in northern Italy was undertaken with several aims: to estimate the N fertiliser value of raw dairy cow slurry, digested dairy cow slurry, and the liquid and solid fractions of the digested slurry, and to verify if applied ammonium recovery was similar both among slurries and between slurries and inorganic N fertiliser (ammonium sulphate).Different fertilisers were applied before silage maize cultivation followed by an unfertilised Italian ryegrass crop. The results showed that ammonium recovery was significantly higher in mineral-fertilised (75%) versus slurry-fertilised (30%) treatments, except in digested slurry (65%). This indicates that ammonium applied with organic materials is less efficient than when applied with mineral fertiliser. For the digested slurry and its liquid fraction, most of the applied ammonium was available to the maize during its application year (55%) due to a low carbon (C)/organic N ratio. The apparent N recovery of the raw slurry and digested slurry solid fraction increased substantially between the first (-1.4%) and second (20%) years, as these materials had high C/organic N ratios; they likely immobilised N for several months post application, producing residual effects during the Italian ryegrass and next maize crops. IntroductionRaw and anaerobically digested livestock slurries can be valuable fertilisers because they supply nutrients and organic matter to the soil.Anaerobic digestion of organic biomasses has seen considerable growth in Europe (Eurobserv'er, 2013) and in northern Italy (Fabbri et al., 2013) over the last decade.Many biogas plants co-digest livestock and biomasses to increase methane production, and in northern Italy, energy crops are often dedicated for co-digestion (Fabbri et al., 2013). To facilitate the use of digested slurries as fertilisers, liquid and solid fractions are separated to ease their transport (Möller and Müller, 2012).A deep understanding of applied slurry nitrogen (N) turnover in soil, and identification of practices to reduce N losses are required to maximise crop N use efficiency and to minimise environmental losses. Nutrient management plans (NMPs) maximise crop N use efficiency through calculation of the slurry amount needed for optimal crop production, and determination of application dates that match crop nutrient requirements according to soil type, local climate, and crop characteristics (Grignani et al., 2003). The slurry N fertiliser value is normally accounted for in a NMP by apparent nitrogen recovery (ANR), an expression of the fraction of applied total N that on average can be taken up by the cro...

This paper reports results from a field experiment established in 1995 and still on going. It is located in Lodi, in the irrigated lowlands of Lombardy, Northern Italy. The experiment compares two rotations: the annual double cropping system, Italian ryegrass + silage maize (R1); and the 6-year rotation, in which three years of double crop Italian ryegrass + silage maize are followed by three years of alfalfa harvested for hay (R6). Each rotation have received two types of dairy manure: i) farmyard manure (FYM); ii) semi-liquid manure (SLM). The intent was to apply to each unit land area the excreta produced by the number of adult dairy cows sustained, in terms of net energy, by the forage produced in each rotation, corresponding to about 6 adult cows ha -1 for R1 and 4 adult cows ha -1 for R6. Manure was applied with (N1) or without (N0) an extra supply of mineral nitrogen (N) in the form of urea. The objectives of this study were: i) to assess whether the recycling of two types of manure in two forage rotation systems can sustain crop yields in the medium and long term without additional N fertilization; ii) to evaluate the nutrient balance of these integrated forage rotations and manure management systems; iii) to compare the effects of farmyard manure and semi-liquid manure on soil organic matter. The application of FYM, compared to SLM, increased yield of silage maize by 19% and alfalfa by 23%, while Italian ryegrass was not influenced by the manure treatment. Yet, silage maize produced 6% more in rotation R6 compared to rotation R1. The mineral nitrogen fertilization increased yield of Italian ryegrass by 11% and of silage maize by 10%. Alfalfa, not directly fertilized with mineral nitrogen, was not influenced by the nitrogen applied to the other crops in rotation. The application of FYM, compared to SLM, increased soil organic matter (SOM) by +37 % for the rotation R1, and by +20% for the rotation R6. Conversely, no significant difference on SOM was observed between R1 and R6 with the application of SLM. However, the maize stover used for composting FYM was produced by crops not included in the rotations R1 and R6, consequently the increase of soil carbon was counterbalanced by a deprivation of carbon in other land areas.