Farmers can use phosphorus fertilisers to increase crop yield in tropical soils

Researchers reviewed the evidence and concluded that applying phosphorus fertilisers to tropical soils could improve crop yield. This is important because tropical soils lose phosphorus very fast, which reduces food yield.

As the world population increases and demands more food, soil fertility is unfortunately declining. Phosphorus is an important nutrient found in the soil, which is required by plants in large quantities to produce a good yield. 

But scientists don’t yet know enough about phosphorus in tropical soils.  

In this work, the authors reviewed what we do know about how phosphorus attaches to soil particles. They summarised research papers and books on the topic.

They said that by the year 2050, tropical soils may have no phosphorus because of the high depletion rate. They also said the lack of phosphorus in the soil could reduce more than 40 % of crop yield. 

But scientists could use ‘models’ to predict if phosphorus can attach to soil particles. The researchers found that some soil properties such as pH (soil acidity), temperature, amount of phosphorus already in the soil, and soil type (sand or clay) determine whether phosphorus will attach to soil particles or not. 

Phosphorus was not lost from acidic or neutral soils (with ‘pH’ between 4.5 to 7.5) and between soil solutions and soil particles. 

The researchers said crop yield could be increased by adding phosphorus fertilisers in poor soils or by adding crop remains back to the soil as manures to re-use the phosphorus in them.

The researchers are from Ghana, and their findings are applicable to sub-Saharan tropical soils. 

Abstract

In tropical soils, phosphorus adsorption is a major key process that controls its availability to crops. Phosphorus is one of the main essential plant nutrients required by the plant in large quantities. Plants absorb P either as the primary monobasic phosphate, H2PO4- ions or smaller amounts of the secondary dibasic phosphate, HPO42- ions and the phosphate ion, PO43-. Inadequate supply of phosphorus to the plant affects its potential yield nor cannot complete the reproductive cycle. Regardless of its importance to crops, it can also reduce more than 40 % of crop yield of the world’s cultivated land. Additionally, P levels in tropical soil have been depleted at a higher rate and according to some estimates from the literature reviewed there will be no P reserve in soil by the year 2050. Phosphate adsorption isotherm studies the interaction of the ions with the oxides and soil and also measures the adsorption capacity of soils. Application of P to crop in the form of fertilisers can be adsorbed by the soil but may not be available for plants restricted with specific adaptations. Application of P containing fertilisers can increase available P in the soil hence increase crop yield which can be used to feed the world’s rapid population growth.

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