The constant increase of livestock production units led to a simultaneous increase of the amounts of animal slurry (AS) produced. However, the area of arable soil available to receive this AS tends to decrease and there is therefore the need to find new possible use for AS.
In Portugal, industrial horticulture is an important activity that co-exists with dairy and pig production and requires important inputs of nutrients. The use of AS as organic fertilizer in horticulture would therefore be a win-win strategy. However, AS hygienization is required before being used in horticulture to avoid contamination of products. Several treatments for slurry hygienization are now available but most of them are very costly and imply some strong modification of the AS management chain.
We propose here to optimize a simple and low cost solution for AS hygienization (by pH modification) that do not generate any new waste and improve the fertilizer value of AS in order to promote a new use for AS and provide new fertilizers/amendments for industrial horticulture. Secondly, the efficiency and environmental and economic impact of these new agricultural practices will be assessed. Namely, solutions for odor and ammonia emissions control needed during the higienization process will also be set-up and optimized: the efficiency of a biofitler using raw materials generally used as susbtrate formulation will be tested and compared with traditional acid scrubbers. The sub-product resulting from biofilters will then be reused as soil amendments.
An integrated approach will be conducted considering the following issues:
a) Hygienization of AS by alkalinization: process optimization.
b) Control of gaseous emissions during the alkalinization process using acid scrubber or biofilter.
c) Hygienization of AS by acidification: process optimization
d) Full characterization of the treated materials with special emphasis on the N , P and C dynamics after soil application
e) Soil application of treated AS and subproducts from the biofilter as organic fertilizers in industrial horticulture.
f) Assessment of the impact of AS hygienization on nutrients dynamics after soil application
g) Evaluation of the economical sustainability of the management chain.

The proposed slurry treatments will be first optimized at laboratory scale and then tested at medium scale in order to provide enough material to be applied. We intend to design a simple and turnkey solution that could be quickly implemented at farm scale. The fertilizer value and environmental impact of hygienized AS and derived material will be compared with traditional fertilizers used in industrial horticulture.