Micro-Water Harvesting and Soil Amendment Increase Grain Yields of Barley on a Heavy-Textured Alkaline Sodic Soil in a Rainfed Mediterranean Environment

Edward G Barrett-Lennard,Dana Mulvany,Glen Riethmuller,Laine Williamson,David Hall,Rushna Munir,Callum Wesley

doi:10.3390/agronomy11040713

Abstract

This paper focuses on the adverse effects of soil sodicity and alkalinity on the growth of barley (Hordeum vulgare L.) in a rainfed environment in south-western Australia. These conditions cause the accumulation of salt (called ‘transient salinity’) in the root zone, which decreases the solute potential of the soil solution, particularly at the end of the growing season as the soil dries. We hypothesized that two approaches could help overcome this stress: (a) improved micro-water harvesting at the soil surface, which would help maintain soil hydration, decreasing the salinity of the soil solution, and (b) soil amelioration using small amounts of gypsum, elemental sulfur or gypsum plus elemental sulfur, which would ensure greater salt leaching. In our experiments, improved micro-water harvesting was achieved using a tillage technique consisting of exaggerated mounds between furrows and the covering of these mounds with plastic sheeting. The combination of the mounds and the application of a low rate of gypsum in the furrow (50 kg ha−1) increased yields of barley grain by 70% in 2019 and by 57% in 2020, relative to a control treatment with conventional tillage, no plastic sheeting and no amendment. These increases in yield were related to changes in ion concentrations in the soil and to changes in apparent electrical conductivity measured with the EM38.

Highlights

This paper focuses on the growth of barley (Hordeum vulgare L.) on a sodic alkaline soil (Vertic Calcic Calcisol) affected by transient salinity and the ability of micro-water harvesting and soil amendment with combinations of gypsum and elemental sulfur to increase yield
2019 had less rainfall for crop growth than 2020, plants were constrained by lack of moisture late in the growing season in each year
In accord with our six hypotheses (H1 to H6), we found that the grain yield of barley was improved by microwater harvesting at the soil surface (H1), and by soil amendment with small amounts of gypsum, elemental sulfur or gypsum plus elemental sulfur (H2)

Summary

Introduction

This paper focuses on the growth of barley (Hordeum vulgare L.) on a sodic alkaline soil (Vertic Calcic Calcisol) affected by transient salinity and the ability of micro-water harvesting and soil amendment with combinations of gypsum and elemental sulfur to increase yield.Soil sodicity is a constraint of global significance. In many Australian soils, the dominant clay is kaolinite [7], which consists of platelet-like crystals approximately 390–560 nm in diameter and 60–120 nm in thickness [8]. The faces of these platelets are negatively charged. ‘Edge-to-face’ flocculation depends on the electrostatic attraction of negatively charged platelet faces with positively charged edges; when the soil becomes alkaline, the positive charges on the edges become surrounded by hydroxyl ions, the net positive charges on the edges are lost, ‘edge-to-face’ flocculation ceases, and the clay disperses [11]

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Conclusion