Analysing inter-rotational productivity and nutrition in a New South Wales radiata pine plantation

Comparisons of plantation scale productive capacity and productivity were undertaken for first and second rotations of Pinus radiata plantation on clay soils in NSW, Australia where rotation length was about 30 years. Over a rotation, where there were no significant additions of nutrients, there were small declines in productivity from the first to the second rotation while productivity increased in the third rotation usually due to changes in management. On sites treated with significant quantities of phosphate fertilizer (50 kg P ha(-1)) in the second rotation, there were significant increases in the productivity of the second rotation with a residual effect into the third rotation. The early growth in the second rotation may be higher than the first rotation but the growth changes with age. Rotation length productivity appears to be related to the magnitude of soil nutrient pools. Nutrients such as calcium, potassium and boron appear to be affecting long term growth even though the foliage levels are much higher than normally considered limiting for growth. Most of the differences in productivity between rotations appear to be related to soil nutrients or management changes while potential genetic gains as estimated from experimental trials, are difficult to identify.