This paper provides key information on 4 no-tillage planters to facilitate adoption by farmers in northern Australia. Four commercial planters (Buffalo All-Flex Convertible slot planter, Buffalo All-Flex Compact slot planter, John Deere Max-Emerge planter and Mason Spring Release (SR) Integral planter) of contrasting design were tested in various configurations under 5 different moisture regimes during drying of a heavy-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 were measured between planters and between configurations under most moisture regimes. Seedling emergence was greatest in Buffalo-Compact planter treatments, less for Buffalo-Convertible and Mason SR Integral treatments 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 wide tine opener, created a high incidence of clods which restricted emergence and led to increased occurrence of unimbibed seeds. Generally, for the 3 tine opener planters, the looser the soil in the furrow, the poorer the emergence. The John Deere Max-Emerge double-disc opener, whilst performing well under moist conditions, generally performed poorly when soil conditions were dry. This planter was on most occasions unable to maintain effective depth control under excessively wet or dry conditions, resulting in lower in-furrow soil moisture and significantly poorer and slower emergence than occurred with the other planters. In-furrow seed-firming presswheels, applying a contact pressure of approximately 4-5 kg/cm of presswheel tyre width, ensured better seed-soil contact and higher emergence levels than twin-inclined over-furrow presswheels. The over-furrow presswheels fitted to the John Deere Max-Emerge planter were often unable to close the slot effectively, resulting in the creation of voids and caps with resultant high seedling mortality.
