Exploring soil amendment strategies with polyacrylamide to improve soil health and oat productivity in a dryland farming ecosystem: One-time versus repeated annual application
Citation
Ma, B., Ma, B.L., McLaughlin, N.B., Mi, J., Yang, Y., Liu, J. (2020). Exploring soil amendment strategies with polyacrylamide to improve soil health and oat productivity in a dryland farming ecosystem: One-time versus repeated annual application. Land Degradation & Development, [online] 31(9), 1176-1192. http://dx.doi.org/10.1002/ldr.3482
Plain language summary
Ever-increasing land degradation from poor farming practices and changing climate scenarios affects soil health, crop productivity and sustainability in dryland farming regions, both locally and globally. Polyacrylamide (PAM) is a synthetic polymer with a super-high water retention capacity. It has been used as a soil amendment on construction sites and on millions of hectares of furrow irrigation lands worldwide to improve soil water holding capacity and stabilize soil structure, thus decreasing soil degradation and erosion. Oat is a small grain cereal crop grown worldwide and is increasingly being used for human consumption as a beneficial health-food.
The specific objective of this paper was to determine the effects of single vs. multiple annual PAM applications on (i) the dynamic changes in soil quality parameters (soil water storage, enzyme activities, and nutrient availability), and (ii) oat crop productivity indicators (grain protein, protein yield and partial factor productivity of nitrogen) in a dryland farming ecosystem.
From this research, we found that one-time PAM application showed measurable increase in water saving ability under drought and land degradation damage, with only a slight improvement in harvestable yield at five years after its application. In contrast, repeated annual PAM application for a minimum of 2-3 years sustained better agricultural ecosystem balance through effective soil water conservation, nutrient turnover, and carbon sequestration in topsoil and deep soils with corresponding increases in grain protein, protein yield, and nitrogen and water use efficiency. Our study implies that annual PAM application is a viable strategy to cope with global climate change and improve soil health and crop productivity in arid and semi-arid regions.
Abstract
Degraded lands resulting from human and natural causes are widespread in arid and semiarid regions throughout the world. Polyacrylamide (PAM) soil amendments are increasingly used to remediate these degraded lands with the potential benefits on soil health and crop production. However, the scientific evidence of farm-scale use of one-time versus repeated application of PAM has not been reported. The specific objective of this research was to determine the effects of single versus multiple annual PAM application on (a) the dynamic changes in soil quality parameters and (b) oat crop productivity indicators in a dryland farming ecosystem. Our data illustrated that multiple years of annual application of PAM significantly increased soil profile water storage, whereas it reduced soil bulk density and electrical conductivity in the top (0–20 cm) and deeper layers (20–60 cm) over those for the control or single PAM application. The improved soil microecological environments led to increased activities of soil enzymes urease (up to 106%), invertase (94%), and catalase (45%). These in turn promoted soil nutrient turnover and availability (e.g., 76% higher soil alkaline N) and crop growth leading to the improvement in grain protein (up to 31%), protein yield (58%), and partial factor productivity of nitrogen (20%), than did the control treatment. Taken together, these soil and crop performance indicators suggest that repeated annual PAM application for a minimum of 2–3 years would be an effective strategy to combat drought and land degradation and foster sustainable crop production in dryland agriculture under a changing climate scenario.