HUMATES used with urea fertiliser can boost pasture production by 10% to 15% over urea alone, while also increasing the longevity of the urea, a five-year trial in Southland has found.
The results have been published in the international science magazine Nature, validating anecdotal evidence humates can help significantly lift pasture production.
Southern Humates owner Malcolm Sinclair says humates form as organic compounds and come from the seams of some lignite deposits.
They consist of complex organic chemicals created by the long-term breakdown of plant material.
It has historically been claimed humates can boost soil fertility by altering bacterial populations, increasing the ability of plants to take up nutrients through their roots.
Sinclair says having the result published in Nature is an endorsement and validation of the trial, done on a farm near Mataura, and the product’s qualities.
“This trial has represented a significant investment in time and funds for us.
“The fact it extended over five years has meant it has cost more than the usual one-year trial but it has delivered results that can give farmers and industry assurance there are real, sustained benefits from humate use in pasture systems,” he says.
The trial was done by soil scientist Peter Espie over a period longer than usual to provide scientific rigour.
Five different combinations of urea-humates were applied by weight, ranging from zero humate to humates equivalent to 20% of the weight of urea applied.
The total urea applied ranged from 160kg to 260kg a hectare a treatment. The drymatter of the pasture grown in each sampled plot was measured for its growth at regular intervals throughout the trial.
Sinclair said it was important to invest in a validated, long-term trial to provide information farmers can trust and prove the anecdotal evidence supporting humates’ value is based on proven yield data.
The trial predictably found use of straight urea increased production but with the addition of humates the production increase was boosted further by the addition of 10% and 20% humates by weight.
The 10% addition of humates generated 9% extra drymatter above that generated by urea alone. The 20% humate generated a 10% increase.
The study found the effect of adding humates is consistent and persistent.
Pasture performance was particularly strong in early spring when nitrogen levels can be limited and the 10% addition delivered a 31% lift in pasture production over standard urea application and a 41% boost when humate levels were increased to 20%.
Adding humates to urea also increased the urea’s longevity with a late summer application continuing to generate positive pasture responses for seven more months.
The report authors suggested coating urea with a bioactive, humic layer could open up opportunities for making nitrogen use more sustainable as the planet grapples with nutrient runoff and groundwater contamination.
Research is under way at Dory in Canterbury to quantify if humates can slow or stop the leaching of nutrients.
Initial research has found humates might reduce the amount of nitrogen available for leaching by helping plant root systems and microbiomes better contain nutrients.
“There is a view that if you get your biology right it holds on to nutrients better,” Sinclair says.
The quality of humates differs according to the age and quality of coal but he warns not all humic products are the same.
The lower the quality of coal the higher the quality of humates and Southland has vast resources of lignite or young coal.
“Variation in the composition and activity of humic products has long been recognised for the inconsistency in plant responses that can be reported.
“We have worked to deliver a consistent product over the years and the results reflect that level of quality.”
Sinclair, an agricultural contractor, stumbled on to the humate business.
To keep staff over the quieter winter months he worked mining coal for domestic Southland use.
A casual meeting with sol scientist Dr Andrew Young introduced him to soil biology then the role of humates.
Two years ago Sinclair sold his contracting business and established Southern Humates and now supplies the product all over NZ with sales increasing because of the growth of regenerative farming.
Farmers mix and apply humates to pasture with existing fertiliser or lime.
