Critérios técnicos para o licenciamento ambiental da suinocultura.

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Maize nitrogen use efficiency is affected by pig slurry composting and anaerobic digestion.

ABSTRACT: We assessed the nitrogen use efficiency of maize amended with mineral and organic N sources in a Nitisol from Southern Brazil under contrasting soil tillage systems: conventional tillage (CT) and no-tillage (NT). The tested N sources were: 140 kg N ha-1 (total N input) either as mineral fertilizer (urea; MIN), pig slurry (PS), anaerobically digested pig slurry (ADS) and composted pig slurry (CS), besides a control without fertilization (CTR). The N-based application of PS and ADS supplied less than 74% of the maize requirements for P2O5 (115 kg ha-1 ), while CS exceeded P2O5 demand by up to 109%. PS and ADS promoted maize N uptake, biomass production and grain yield similar or higher than maize receiving mineral fertilizer (urea). However, CS promoted significantly lower N agronomic efficiency (AEN) and recovery efficiency (REN) than other fertilizers. CS should be primarily used as a source of P and K or as an amendment to recover SOM stocks in degraded soils

Soil organic carbon pools as affected by tillage systems and organic nitrogen sources.

ABSTRACT: We assessed the impact of organic N sources on total organic carbon (TOC), particulate organic carbon (POC), and mineral-associated organic carbon (MAOC) pools in a Nitisol from Southern Brazil under contrasting soil tillage systems. The tillage systems were conventional tillage (CT) and no-tillage (NT). The tested N sources were: 140 kg N ha-1 (total N input) either as mineral fertilizer (urea; MIN), pig slurry (PS), anaerobically digested pig slurry (ADS) and composted pig slurry (CS), besides a control without fertilization (CTR). TOC stocks decreased by 1.0 and 5.1 Mg C ha-1 after two years of CT in both 0-5 and 0-30 cm soil layers, respectively. NT increased TOC stocks by 2.3 Mg C ha-1 at the soil surface and decrease by 1.7 Mg C ha-1 at the 0-30 cm soil layer. NT had higher POC and MAOC stocks than the CT soil. POC was a more sensitive pool than MAOC in response to soil tillage and fertilization practices. Long-term and continuous assessment of SOC pools is needed for evaluation of the impact of organic N sources for C sequestration in NT soil

Struvite crystallization mitigates reactive N losses from swine manure in-vessel composting.

ABSTRACT: We assessed the addition Mg and P salts to promote struvite crystallization and mitigate reactive N losses from a rotating drum (12 m3 ) used for in-vessel composting of swine manure. The tested treatments were: mixture of sawdust and swine manure (baseline) and the same mixture with the addition of magnesium sulfate and phosphoric acid (MgSO4+H3PO4). Struvite crystallization decreased NH3-N and TN losses by 96.5 and 46%, respectively. Higher N2O-N emissions were related with resolubilization of the struvite under lower pH conditions. Further research is needed to assess strategies for the stabilization of struvite crystals, minoring N losses and increasing nutrient concentration value of the organic compost