Reduced fertilizer use to curb soil fertility
Cuts in fertilizer use due to record high prices will deplete soil’s nutrient reserves and lead to declining soil fertility on farms, Teagasc warned.
Nearly 60 percent of grassland on dry stick farms now has a need for lime, a Teagasc review of 2022 soil test results has shown.
The results show that 47 percent of the dairy farm samples and 57 percent of the dry farm samples have pH values below the target pH of greater than 6.3. On arable farms, overall soil pH is higher, but 39 percent of soils still remain below the target soil pH of greater than 6.5.
According to Teagasc, early indications are that lime consumption will exceed one million tons in 2022 for the second year in a row.
Mark Plunkett, Soil and Plant Nutrition Specialist at Teagasc, said that lime application is now a priority on grassland and arable farms as P and K fertilizer application has been greatly reduced (-25 percent).
“Lime now plays an important role in regulating soil N, P and K supply and the efficient use of applied nutrients in the form of cattle manure and chemical fertilizers,” he said.
“These lime applications will reduce soil acidity in years to come, but further correction of soil pH on farms will be crucial to increase fertilizer use efficiency, particularly where P and K fertilizer use is critical due to rising fertilizer costs in recent years,” he said.
Overall, soil fertility showed some positive trends, with a stabilization in the proportion of soils with overall optimal soil fertility for pH, P and K on both dry livestock and arable farms, while dairy farms showed an improvement in soil fertility in 2022.
All farm types showed an improvement in soil P and K fertility, with the exception of arable farms, where soil K levels decreased slightly for the first time in 11 years.
Soil samples from dairy farms show a 4 percent increase in soils with optimal soil fertility to a total of 20 percent.
Soil with optimal fertility on arable farms increased slightly to the current 19 percent, while soil fertility on dry livestock farms remained unchanged at just 13 percent within the optimal range for pH, P and K.
dr David Wall, soil fertility researcher at Teagasc, said farmers need to be aware of what has happened to fertilizer use on the farms over the past year.
“Unfortunately, if reduced fertilizer (P&K) use continues in 2023, it will likely result in a further decrease in soil nutrient reserves and declining soil fertility.
“These potential reductions in soil fertility will not be recognized until these fields are sampled again in a few years.
“Soil fertility is a critical determinant of nitrogen use efficiency and crop yield, and plans must be put in place to protect agricultural soil productivity and long-term farm sustainability.”
https://www.independent.ie/business/farming/dairy/reduced-fertiliser-use-to-curb-soil-fertility-42330199.html Reduced fertilizer use to curb soil fertility