Impacts of biostimulants on soil health and crop yield

  • Jenendra Wadduwage

Western Sydney University thesis: Doctoral thesis

Abstract

Expansion of arable farming and use of synthetic chemicals (fertilisers and pesticides) are expected to increase in order to feed the ever-growing global population. However, in many countries further increase in inorganic fertilisers do not translate into increased farm yields. In addition, excessive and inappropriate use of synthetic chemicals has led to detrimental impacts on human and environmental health including widespread water pollution, soil fertility loss and accelerated greenhouse gas emissions. Global food demand is expected to increase by 70% by 2050. Given the lack of productivity gain from further chemical inputs, new non-conventional sustainable farming approaches may be required to increase the food production and ensure environmental sustainability. The use of biostimulants alone or in combination with inorganic fertilisers provide a promising alternative to sustainably increase crop yield via improving soil health. However, the extent and exact mechanisms by which biostimulants improve soil health and farm productivity is not fully known. The overarching aim of this thesis was to evaluate the impacts and mechanisms of biostimulants on key soil biological health components and consequences for crop yields. Two field-based experiments and a glasshouse experiment including different cropping systems (arable, pasture and horticulture) were conducted. Soil biological and physicochemical properties and crop yield were measured, providing quantitative knowledge on the impacts, magnitude, and mechanisms of biostimulants application on soil health. Such knowledge will help in large-scale adoption of biostimulants approaches by farming communities. In Chapter 2, the impacts of sole and combined application of two biostimulants (Universal Natural Plant food - UNP and Converte Seed Primer - CSP) on soil health were examined under broadacre farming systems. In Chapter 3, the impacts of sole and combined application of biostimulants with inorganic fertilisers on soil health and yield of different pumpkin varieties were studied under horticultural farming systems. In Chapter 4, the impacts of sole and combined application of biostimulants with an inorganic fertiliser were studied under drought stress conditions for two soil types using a lettuce crop. Overall, this study provides quantitative knowledge on the impacts, magnitude, and mechanisms by biostimulants alone or in combination with inorganic fertilisers improve soil health and crop yield for different crops, farming systems and soil types. Such knowledge is critical to advance large-scale adoption of biostimulant approaches by farming communities.
Date of Award2021
Original languageEnglish

Keywords

  • plant growth promoting substances
  • crop yields
  • soils
  • quality
  • soil productivity

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