Water productivity and net profit of high-density olive orchards in San Juan, Argentina

Abstract

Olive cultivation in Argentina has experienced an important expansion based on large-scale development of high-density (HD) olive orchards. Intensification has led to yield increases, but, because of the high annual ETo and low rainfall, olive production must rely heavily on irrigation. The aim of this work was to determine the yield response to variable water supply of a HD, tall olive orchard, and to assess the economic water productivity (WP) of the olive, growing in an environment where the water resource is extremely scarce. During three seasons in an olive orchard (cv. “Arbequina”), we evaluated seven irrigation regimes which supplied 120% (T120), 100% (T100), 90% (T90), 80% (T80), 70% (T70), 60% (T60) y 40% (T40) of the estimated ETc. After the first year, which was considered of transition, the next two growing seasons exhibited a clear decline in yield in response to the irrigation decline, with the reduction in fruit yield related to both fruit numbers and fruit size. A third degree polynomial function was fitted to treatment averages (R2 = 0.99). The maximum oil production (ca = 3080 kg oil ha-1) was obtained with 860 mm of irrigation. The marginal WP reached a maximum (5.9 kg oil ha-1 mm-1) at 550 mm of irrigation and declined thereafter, reaching zero at 860 mm. In economic terms, the grower achieves maximum returns (US$ 3140 ha-1) at 850 mm of irrigation. With the cost of water increasing from the present US$ 0.04 m-3 to US$0.24 m-3, the maximum net profit would be reduced by up to 53% (US$ 1476 ha-1), however, it would be achieved at a similar irrigation level (820 mm). If in the near future water scarcity in the region makes it difficult to maintain the present levels of water supply, aimed at maximizing profits, there will be the need to impose restrictions through resource conservation policies to reach an equilibrium between economic, environmental, and sustainability goals.