PhilRice cites importance of biomass to maintain soil nutrients

SCIENCE CITY OF MUNOZ, Nueva Ecija, Sept. 22 (PNA) –The Philippine Rice Research Institute (PhilRice) has cited the importance of using biomass on rice fields in order to maintain soil productivity.

In a PhilRice study titled “Soil Properties of Major Irrigated Rice Areas in the Philippines,” it identified the factors that affect soil properties and significance of biomass and biochar in restoring the lost nutrients brought by farm management practices.

Jehru Magahud, lead researcher, said continuous high-yield cropping affects soil pH (measure of alkalinity or acidity) wherein the amount of soil nutrients are removed during the crop uptake.

“Modern irrigated rice varieties remove 17.0 kg potassium, 4.0 kg calcium, and 3.5 kg magnesium in every ton of grain yield,” he said.

When the soil’s pH goes down to 5.5 (strongly acidic), the availability of some essential nutrients is reduced.

He also noted that at such state, the phosphorus level is very low.

This contributes to low yield gains, and generally as a preventive measure, farmers address the problem through commercial and chemical fertilizers.

The study noted that generally, the Philippine paddy soil is slight to strongly acidic.

Out of the 30 areas where the study was conducted, the Central Luzon soils have the most acidic state.

Throughout the duration of the study, low available phosphorus levels were noted in the area brought by strongly acidic pH.

Magahud said that aside from using commercial and chemical fertilizers, farmers of these areas should incorporate biomass, manures, and biochar to restore normal pH levels and organic matter contents.

Biomass utilization from farm by-products can help farmers save expenses from chemical fertilizer inputs.

Biomass includes rice straw and other rice residues.

“It is the most practical way to replenish low levels of available nutrients,” he said.

Biochar also increases the nutrient and water-holding capacity of the soil.

“The carbonized rice hull contains phosphorus, potassium, calcium, magnesium, and other micronutrients vital to growing crops. When mixed with other organic materials, it improves soil structure by increasing its bulk density, aeration, and water holding capacity,” Magahud said.

Biochar is also a natural habitat for beneficial organisms that facilitate composting.

He recommended using biomass and biochar on soils with low level of phosphorus and strongly acidic pH and for sandy soils with limited water retention. (PNA)