A Framework of Tradeoffs in Soil Health: A Case Study of Soil Carbon and Salt Accumulation in an Arid Agroecosystem

Abstract:

Particularly in irrigated arid landscapes with low primary productivity, management for soil health can exceed the baseline function of the natural system. Defining soil health potential from a ‘natural baseline’ therefore proves less informative for these types of landscapes and requires a different framework. When soil health metrics are tightly linked to soil processes, a comparison of soil functional response between different management treatments, such as irrigation, can provide critical information to decision-makers. In the hyper-arid region of Arequipa, Peru, flood irrigation has historically been used for perennial crops, such as vineyards. Over the last three decades, producers have transitioned to using drip irrigation. Although drip irrigation drastically reduces water inputs, it also results in less flushing of salts from the soil. To assess effects of the shift in irrigation strategies, we measured soil health parameters across three vineyards with different amounts of time under drip irrigation (9, 15, 35 years). We present results centered on assessment on soil carbon of bulk soil and size/density fractions and visible near infrared spectroscopy. Additional soil chemical properties, including salt content were measured for future comparison to results from field soil health test kits. In this way, we are leveraging these arid sites to quantify tradeoffs between positive goals of soil health and carbon accumulation and negative effects of salt accumulation. This dataset provides an example of how soil health can also serve as a framework for tradeoffs between ecosystem services and negative externalities. The results also contribute to a larger project to determine the most efficient measurement techniques for soil health in arid, low productivity systems.