## 1 Introduction  
Processed nitrogen products from livestock manure, so-called RENURE products (REcovered Nitrogen from manURE), have the potential to substitute chemical fertilizers, and, in combination with good agricultural management practices, these products might increase resource efficiency in food systems and decrease ammonia (NH\({}_{3}\)) and greenhouse gas (GHG) emissions [1]. One of these products is liquid ammonium sulfate (AS), which is produced by separating digested dairy slurry into a liquid and a solid fraction, and applying stripper/scrubber technology to the liquid fraction [2]. In the stripper, some of the ammonium in the solution is transferred to the air as ammonia by heating the digeste and/or by increasing the pH. In the scrubber, the ammonia is washed out of the air into a sulfuric acid solution, creating AS. Other fertilizers from this production process include the N-stripped liquid fraction, which is a potential K fertilizer but still contains organic nitrogen. Furthermore, the digeste is separated into a solid and liquid fraction by a screw press. The resulting solid fraction, rich in organic matter, can be processed further by extracting the P, resulting in a P-rich sludge fertilizer and a low-P organic fertilizer [3].  
We assume that the use of processed manure products can balance N, P, and K fertilisation of the crop more than the original livestock manure [4]. However, it is not clear whether, and in what conditions, the processed manure products result in efficient fertilizers with low emissions. The efficiency of a nitrogen-delivering fertilizer is often tested by determining the nitrogen fertilizer replacement value (NFRV): an index that compares the effect of a fertilizer of interest on a crop to a well-known mineral N fertilizer [5; 6]. The gaseous emissions of new fertilizers are often determined at multiple points in time. Subsequently cumulative N emissions per kg of N fertilized can be determined by the integration of the gaseous emissions over time and thus can be compared to fertilizers with well-known emission factors [7; 8]. Another method to determine emission factors is to measure emissions continuously over time during a relevant period [9]. Our aim is to assess whether AS from processed manure has the same agronomic value as mineral nitrogen, for different soils and crops. Additionally, the effect of these fertilizers on GHG and NH\({}_{3}\) emissions will be determined, since the carbon in AS can influence the GHG emissions [10], and the NH\({}_{4}\) content of AS can influence NH\({}_{3}\) emission [11]. The number of experiments conducted on these novel fertilizers is still limited [2; 12]; although, AS and other nitrogen products from processed livestock manure are likely to be included in the Commission Directive (draft) amending Council Directive 91/676/EEC (European Nitrate Directive) as a specific nitrogen fertilizer that may be applied as substitute for mineral fertilizers up to 100 kg N ha\({}^{-1}\)[13]. Our hypotheses are:  
1. Ammonium sulfate from the manure stripping process (AS) has the same nitrogen use efficiency as mineral nitrogen fertilizer in a clay soil with a relative high pH (pH > 7) (20), and a sandy soil with a normal pH (pH < 7) (20), for maize and grass. Maize and grass are the relevant crops for livestock farming in The Netherlands.
2. NH\({}_{3}\) and GHG emissions, in this research: methane (CH\({}_{4}\)) and nitrous oxide (N\({}_{2}\)O) are influenced by soil type, soil pH, and the fertilizers.
3. NH\({}_{3}\) emissions of liquid ammonium sulfate obtained from processed manure are lower than for the original livestock manure, while the NH\({}_{3}\) emissions from the remaining treated products (the solid fraction of the digestate and the stripped liquid digestate) are similar or slightly higher than the original livestock manure, resulting in the lower net emission of the processed products compared to the original manure.