The performance of CSIRO varieties and new lines are evaluated each year in a series of regional trials, known as the Australian Cotton Cultivar Trial (ACCD. CSIRO and the QDPI have been running these trials since the 1974175 season. Currently the ACCT comprises thirteen sites representing all the major cotton growing areas. This wide testing provides a good estimate of overall performance while also enabling assessment of whether particular genotypes perform relatively better at some environments than others.

Raingrown cotton requires a considerable financial outlay hence many farmers seek to reduce their exposure or to 'hedge their bets' by planting in skip row configurations. Skip row provides a reserve of soil moisture beside the planted rows and use of these 'side' reserves extends, by a number of days, the period that a crop can continue to photosynthesise at a certain level compared to a solid planted crop. If effective rain occurs during this extension of time, it can translate to a yield increase and possible quality improvement. A deep profile of stored moisture works in exactly the same fashion, but this deep reserve is smaller than the skip reserve - combine the two, however, and the odds for a successful crop in a dry season are markedly improved. Figure 1 shows that the extra stored moisture at planting bas a big influence on final yield, especially in a dry year. Figure 2 shows how a skip row configuration extends the time period that higher levels of soil moisture are available to the crop. The plant is able to draw moisture from a distance of at least 2 metres from the plant line, drying the soil to the same degree as immediately below the row.

CSD conducts large scale variety trials in all the cotton growing districts each season. It is well known that variety performance often differs markedly from season to season. It is therefore desirable when choosing which varieties to grow to study results for as many seasons as possible. This has been done for a number of districts using the average variety yields from all the CSD trials conducted in various districts as a percentage of the CSIRO variety, Siokra 1-4. This variety in recent years has been included as the standard for comparison in all the trials. The Pioneer - Deltapine variety Deltapine - Acala 90 (DP90), grown in Australia for a number of years has also been included in almost all the CSD trials and its performance relative to Siokra 1-4 is also included. In some cases where a new variety has only had limited testing but is closely related to its predecessor (e.g. Sicala V-1 and Sicala V-2; and Siokra L22 and Siokra L23) results are combined ro allow a longer tenn perspective of performance

Rainfed or dryland cotton grown in the 550 to 600 mm. per year rainfall regions of northern N.S.W. and southern Qld. is a profitable summer crop alternative. The rainfall distribution tends to be slightly summer dominant while suitable soil has plant available water capacity of 1 00 to 140 mm. of water. The variability of in crop rainfall especially during late December and January co-incides with the maximum water needs of the crop, thus good sub-soiJ moisture is essential to reduce the risk of crop failure. In addition, soil surface in the crop needs to be rough with open cracks, or have a stubble cover to capture high intensity rain especially on sloping areas.

Attendees at the 1992 Australian Cotton Conference sat in silence as two speakers promoted completely opposite approaches to insect pest management in raingrown cotton. Here, I have explored the apparent discrepancies between the approaches and conclude both were correct - dependant upon their economic considerations.

In recent years Cotton Seed Distributors (CSD) have made available a range of CSIRO varieties with different attributes, thus enabling farmers to choose varieties best suited to their particular situation. For 1994 plantings CSD have available three new CSIRO varieties: Sicala V-2, Siokra V-15 and CS 8S. All were developed for particular situations but are showing broader adaptation than expected

Raingrown cotton is becoming a very important component of the Australian industry: the relative proportion of the crop grown with rain has been increasing over the past ten years. Given good prices and rainfall, the area of the crop grown with rain will exceed 50,000 ha. It is also important to note that during droughts, irrigators are forced to grow cotton semi-raingrown. This article aims to point out principles and results which aid the decision as to which variety to grow under raingrown conditions. Data from raingrown experiments are presented. We also illustrate some primary points for crop water use/supply/response.

Watertable rises resulting from irrigation are evident in several areas in the Murray Darling Basin, with groundwater level rises of up to 70 cm per year being reported in the Riverina and 50 cm in the Lower Macquarie Valley. The Department of Water Resources initially reported rising groundwater in the Lower Macquarie Valley about 7 years ago, and it was predicted that large areas north and west of Narromine may become waterlogged within the next 15 - 25 years. Current aquifer pressures indicate watertables may rise to within 2 m of the soil surface in some areas, eventually resulting in salinisation. Groundwater recharge in the Macquarie region seems to be effected by a number of factors including; floods, seepage from the river bed; leakage from weirs; storage dams and irrigation channels; and intensive irrigation. The aim of this study was to identify potential rates of groundwater recharge under irrigated cotton.

There are both anecdotal and well documented reports indicating that unsprayed cotton can be profitable. However, the frequency of growing a profitable crop in this way has not been established and the pathway to success is not well worn. On the other side of the coin, the use of insecticides increases the probability of profitable returns, but this approach to pest management is not without its problems

Permanent beds are becoming popular in the cotton industry, but problems remain with matching equipment and tyre sizes to the beds and furrows. Decisions about tyre sizes ad equipment matching require information about the impact of the equipment on soil compaction in the furrow and bed. In this paper we study: 1. the impact of narrow and wide tyres on the furrows in a pennanent bed system; and 2. the effect of furrow shape.