Researchers from PhilRice recommended using biomass on rice fields to maintain soil productivity. Soil-PhilRice

Jehru Magahud, lead researcher, identified the factors that affect soil properties and significance of biomass and biochar in restoring the lost nutrients brought by farm management practices.

Magahud said that continuous high-yield cropping affects soil pH (measure of alkalinity or acidity). Amounts 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 stressed 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.

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.

“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 explained.

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

For more information about biomass and biochar utilization, call or text the PhilRice Text Center 0920 911 1398.

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Philippine Rice Research Institute (PhilRice) is a government corporate entity attached to the Department of Agriculture created through Executive Order 1061 on 5 November 1985 (as amended) to help develop high-yielding and cost-reducing technologies so farmers can produce enough rice for all Filipinos.

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Philippine Rice Research Institute