The effect of municipal solid waste compost application on soil water and water stress in irrigated corn

Land application of municipal solid waste (MSW) compost increases soil organic matter content and influences soil physical properties. This study was conducted to measure the effect of compost on the water holding capacity of soil and water status in corn (Zea mays L.) from 1993 to 1995. The soil was a Hubbard loamy sand (sandy, mixed, Udorthentic Haploboroll) cropped to irrigated corn at the Sand Plain Research Farm at Becker, MN. Compost treatments on dry weight basis were 0 and 90 Mg ha^-1 yr^-1 from 1993 to 1995, and a one time application at 270 Mg ha^-1 in 1993. The soil moisture retention curves were generated in 1994 and corn leaf water potential and soil bulk density were measured each growing season. Based on water retention curves, the addition of compost increased the water holding capacity of soil without significant increase in the estimated available water. This was contradicted by field measurements which showed that compared to a fertilized control one compost source at the 270 Mg ha^-1 rate in the year of application increased plant water stress by 0.22 MPa, likely due to salt loading. In the year after the application of the 270 Mg ha^-1, two compost sources increased soil water content and corn yield 0.14 cm³ cm^-3 and 0.9 Mg ha^-1 respectively. The yield increase was also associated with a reduction in plant water stress of 0.14 MPa due to one of the compost sources.