[Animal wastes can reduce fertilization costs]

abonos npk abonos organominerales analisi dei costi aves de corral azote azoto bovin bovini cattle cerdo compost composts concimi npk concimi organici contenido de materia seca contenuto di sostanza secca cost analysis dry matter content engrais npk engrais organique faeces farmyard manure feces feci fertilizzanti organominerali fosforo fumier ganado bovino heces letame liquami liquid manures market prices nitrogen npk fertilizers nutritive value organic fertilizers organic matter organomineral fertilizers phosphore phosphorus pollame porcin potasio potassio potassium poultry precios de mercado prezzi di mercato purin sostanza organica suini swine valeur nutritive valor nutritivo valore nutritivo volaille