在四个试验小区比较三种淋洗与改良策略——哪一种在经济上划算？
Between 2023 and 2025 we compared three salinity management strategies across four trial plots in a pistachio orchard with saturated-extract electrical conductivity between 6 and 8 dS/m. The aim was to find a strategy that both lowers root-zone salinity and is defensible in terms of water use.
Trial design
- Control plot: the grower's existing management, unchanged.
- Plot A: a single heavy winter leaching event.
- Plot B: leaching split across four applications through the season.
- Plot C: split leaching combined with granulated gypsum applied at the start of the period.
Main findings
Despite high water use, Plot A produced no durable reduction in salinity; conductivity returned to baseline by mid-season. Plot B performed better, but without structural remediation infiltration remained the limiting factor.
Plot C gave the best outcome: root-zone conductivity down to about 4.2 dS/m by the end of year two, using less water than Plot A. The reason is straightforward — by displacing sodium, gypsum improved infiltration and made leaching more effective.
The economics
The cost of granulated gypsum in Plot C was significant in year one, but counting water saved and the yield gain in year two, payback worked out at under two seasons. In Plot A the extra water, with no durable result, was effectively a net cost.
On sodic soils, leaching without structural remediation looks less like salinity management and more like wasting water.
Limitations
The trial ran at a single site on one cultivar, so generalising the results warrants caution. Irrigation water quality also varied over the period; this is accounted for in the analysis but its effect cannot be fully isolated.