Inoculant Formulations and Applications to Meet Changing Needs

Abstract

Legume inoculants provide a means for transporting superior nitrogen-fixing rhizobia from the fermentor to the legume field. A high quality formulation and application must maintain and deliver, in a convenient and economical fashion, a high population of effective rhizobia. Soybeans are a major worldwide legume and constitute a high percentage of total inoculum use. Soybeans in the USA under intense cropping systems are being planted and managed in a changing manner to improve soil conservation. Conservation tillage is a system of cultivation and crop residue management that maintains at least 30% crop residue on the soil surface (Dickey et al., 1994). No-till, ridge-till, strip-till, and mulch-till are examples of conservation tillage. Forty-six percent of the US soybeans were under conservation tillage in 1994 with the majority of this production utilizing narrow-row planting (18–30 cm) instead of the more common 76–91 cm row width with conventional tillage (Johnson, 1994). Drills are frequently used for narrow-row plantings and, in addition, air or vacuum planters are replacing the plate planters in wide rows.