Previous PageTable Of ContentsNext Page

FIELD PEA YIELDS ARE DECLINING IN MEDIUM TO HIGH YIELDING AREAS

D.M. Peck and G.K. McDonald

Department of Plant Science, Waite Agricultural Research Institute,Glen Osmond, 5064.

Abstract

Trends in production and yield of field pea (Pisum sativum L.) between 1983 and 1994 were examined for statistical areas in South Australia, Victoria and New South Wales. In each state average yields have declined by between 24% and 38%, but the decline was most evident in South Australia. Those parts of South Australia that showed significant reductions in yield produce 26% of the state's crop whereas in New South Wales only 10% of production was derived from areas with significant yield decline. The significant yield declines occurred in areas which initially had high yields. This review of field pea production shows that significant yield declines have occurred and research is required to identify the most likely causes of the decline and how to manage field peas for maximum yield and rotational benefit.

Key words: field pea, yield trend.

Field pea is the most important pulse crop in southern Australia but there is a widespread perception among farmers that yields have not increased significantly or have declined over the past two decades. This concern about the productivity of peas has coincided with a large increase in production and the development of field peas as a significant crop across southern Australia. McDonald (1) examined yield trends in parts of South Australia between 1960 and 1991 and found yields increased substantially until the 1980's, but since then there has been little further change. There was evidence of a decline in yield in some areas, but the trends were not clear cut. This analysis was limited to a small number of statistical regions in South Australia and did not examine trends in Victoria and New South Wales. Given the concern about yield decline over southern Australia, we conducted a further analysis of yields of peas throughout the cropping zones of South Australia, Victoria and New South Wales.

Methods

Unpublished Australian agricultural census data on the area and production of field peas were obtained for statistical local areas in South Australia, Victoria and New South Wales from the Australian Bureau of Statistics. A linear regression was fitted to yields from statistical local areas that grew at least 1000 ha/yr of peas at least once and grew peas from 1983 onwards for South Australia and Victoria and from 1984 onwards in the case of New South Wales. Yield trends of local areas within each state were compared by plotting yield trend against estimated initial yield.

Results

There was a large increase in area of field peas in each state until 1987 after which time areas showed little further increase in New South Wales and Victoria and in South Australia the rate of increase slowed (Fig. 1). The increase in area was accompanied by a decline in yield of 30% in South Australia, 24% in Victoria and 38% in New South Wales. However, there was considerable year to year variation and only in South Australia was the linear trend significant (r = -0.66, P=0.05).

For most local areas the linear trend in yield was not significant (Fig. 2), but twelve statistical local areas in South Australia and two in New South Wales had significant yield declines. These areas produced 26% of total pea production of South Australia from 1983 to 1994, and 10 % of total production of New South Wales from 1984 to 1994. Yield decline was greater the higher the initial yield was. Yield decline was not related to rate of area increase.

Discussion

The general trend in the majority of statistical local areas was for declining yields, but this was particularly evident in areas with high initial yields. However, the variation in yield was high and many of the trends were not significant. Nevertheless, what is of concern is that in South Australia the areas with significant yield decline produced 26% of the pea crop between 1983 and 1994; in New South Wales 10 % of crop was from areas with yield decline. The amount of yield decline was also of concern with areas with significant decline ranging from 43 kg/ha/yr to 126 kg/ha/yr.

To achieve the observed increase in area of peas it is likely that the frequency of pea crops in a rotation has increased. Ramsey and Davidson (2) reported that peas grown in closer rotations ( 2-5 years) have higher levels of the disease black spot than those with longer rotations. It is likely that the frequency of field peas has increased which has resulted in higher levels of disease and hence lower yields.

Conclusion

We have identified local areas in South Australia and New South Wales in which field peas is suffering significant yield declines. These areas were initially the high yielding sites. Causes of the yield decline are largely speculative at this stage and research should be done in some of the worse affected areas to identify causes of the decline and ways to minimise or reverse the decline.

Acknowledgement

We acknowledge the GRDC for providing funds to conduct this research and the Australian Bureau of Statistics for providing the field pea production figures.

Reference

1. McDonald G.K. 1995. Aust. J. Exp. Agric. 35, 515-23.

2. Ramsey, R. and Davidson, J. 1997. Proc. Farming Systems Developments Work. Adelaide. pp. 63-64.

Previous PageTop Of PageNext Page

...

Search Site