DOI LINK: https://doi.org/10.59671/Znb77

Paper ID:Znb77

Volume:262

Issue:5

Title:Effects of a microbial-based soil conditioner on nitrate leaching.

Abstract:The biological activity in soil is important to ensure plant growth and prevent leaching. However, soils that have been exposed to inorganic minerals and acidic chemicals have a depleted microbiome. Replacing this using specialised probiotics can reverse these problems. In this trial, lysimeters to collect ground water leachate were set up to measure the effect of microbial-based soil and plant products (MagnifyNZ Ltd) on nitrate leaching on a dairy farm in Canterbury (2.5 cows/ha). MagnifyNZ fermentation products establish an effective soil microbiome, creating opportunity for high output-low input agriculture/horticulture. The soils were stony shallow silt loams (400 mm deep), classified as Ruapuna and Darnley (medium and high leaching). Fertiliser was applied monthly to provide 190 kg of N/ha/yr. Two treatments were used (soil conditioner and plant biostimulant) in September 2022, January and August 2023 using Magni-Life (2 l/ha) and Magni-Grow (7 l/ha), with and without stored urine, to mimic cow N contributions (600 kg N/ha). The untreated control was Ruapuna soil using the same applications. Lysimeters generated 3-4 drainage collections monthly. Non-urine soil leaching averaged 0.77 mg NO3-N/l for the MagnifyNZ samples compared to 3.98 mg NO3-N/l (P<0.0001) for the control. There was no significant difference in drainage volumes between treatments, which was 325 mm from 901 mm rainfall plus irrigation over 12 months. Urine patch N lasted 40 d in MagnifyNZ soil versus 215 d for the control. Total nitrate loss was 1.18 and 15.04 mg NO3-N/l for the MagnifyNZ treatment and control, respectively (P<0.0001). For the year starting September 2022, estimated total leaching was 3.1 kg N/ha for the treated soils versus 48.99 kg N/ha for the control, compared to 17.15 kg N/ha for the calculated dicyandiamide (DCD) response (Di and Cameron, 2007). There was a 91% reduction in total nitrate leaching from the MagnifyNZ treatment, due to a more stable microbiome which affected absorption of available N by pasture and soil microbes. Modelling the results for DCD (Di and Cameron, 2007) using 600 kg N/ha urine, DCD’s would have given 20-65% reduction in leaching.

Keywords:nitrate, leaching, microbial ,soil conditioner, nitrate inhibitor, DCD, biostimulant,

Authors:S.H. Hobson, J.F. Field-Dodgson, L.A. Waldron

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