NO-TILLAGE PLANTERS FOR HEAVY-TEXTURED ALFISOLS IN THE SEMIARID TROPICS OF AUSTRALIA

This paper provides key information on 4 no-tillage planters to facili tate adoption by farmers in northern Australia. Four commercial plante rs (Buffalo All-Flex Convertible slot planter, Buffalo All-Flex Compac t slot planter, John Deere Max-Emerge planter and Mason Spring Release (SR) Integral planter) of contrasting design were tested in various c onfigurations under 5 different moisture regimes during drying of a he avy-textured Alfisol at Katherine Research Station, Northern Territory , Australia (14 degrees 20'S, 132 degrees 20'E, 108 m altitude) at the end of the 1982-83 wet season. Significant differences in emergence w ere measured between planters and between configurations under most mo isture regimes. Seedling emergence was greatest in Buffalo-Compact pla nter treatments, less for Buffalo-Convertible and Mason SR Integral tr eatments and lowest for John Deere Max-Emerge treatments. The Buffalo planters, each with an effective trash cutting coulter and narrow tine slot opener, produced consistently better results under all moisture regimes than the other 2 planters. The Mason SR Integral, with its wid e tine opener, created a high incidence of clods which restricted emer gence and led to increased occurrence of unimbibed seeds. Generally, f or the 3 tine opener planters, the looser the soil in the furrow, the poorer the emergence. The John Deere Max-Emerge double-disc opener, wh ilst performing well under moist conditions, generally performed poorl y when soil conditions were dry. This planter was on most occasions un able to maintain effective depth control under excessively wet or dry conditions, resulting in lower in-furrow soil moisture and significant ly poorer and slower emergence than occurred with the other planters. In-furrow seed-firming presswheels, applying a contact pressure of app roximately 4-5 kg/cm of presswheel tyre width, ensured better seed-soi l contact and higher emergence levels than twin-inclined over-furrow p resswheels. The over-furrow presswheels fitted to the John Deere Max-E merge planter were often unable to close the slot effectively, resulti ng in the creation of voids and caps with resultant high seedling mort ality.