Abstract Genetically engineered pigs use efficiently phytate phosphorus (P), a major group of P compounds contained in diets, and excrete manures with low P contents. However, the low-P manure (LPSM) has to be agronomically and environmentally assessed before the new technology is practically adopted. An experiment was carried out to evaluate the effects of LPSM from genetically modified swine on dynamics of soil physical properties of a sandy loam soil under controlled greenhouse conditions. Treatments included two types of manures respectively from conventional swine and transgenic swine, both with initial water regimes of 60 and 80% of water holding capacity. Application of LPSM increased mean soil temperature by 0.2ºC during the 30 d period, regardless of soil moisture conditions. LPSM increased soil bulk density by 6.3%, and decreased soil porosity. However, while increasing permanent wilting point, LPSM had subtle effect on water holding capacity, and thus led to reduced available soil water content. It appears that agricultural application strategies for LPSM may be different from that for the conventional swine manure.

Key words: transgenic low-phosphorus swine manure, water stress, soil temperature, water holding capacity, permanent wilting point.