Govt should boost soil nutrients to maintain yields, say scientists

A mapping of India's soil health has shown that almost 90 per cent of the land is deficient in nitrogen and phosphorus, and 50 per cent in potassium

India will have to supplement crucial nutrients in its soils through large dosages of organic manure if it wants to maintain the average crop yields as being a tropical country its percentage of organic carbon in soil is less than one, according to scientists gathered at the Global Soil Conference here on Tuesday to address challenges related to soil health.

 

The requirement of organic manure to provide for the crucial soil nutrient of nitrogen, phosphorus and potassium is huge, they opined.  

 

But, the good news is that between 2019 and 2023, the average NPK ratio in Indian soil has improved and come closer to the ideal 4:2:1 due to differential pricing and awareness on soil health among farmers due to usage of soil health cards. The NPK ratio was at around 8:4:1 in 2019, while last year it was recorded at 5:1.8:1, closer to the ideal ratio.

 

The NPK ratio is the ratio of nitrogen, phosphorus, and potassium in a fertilizer.

 

Citing an example of paddy and usage of organic manure, Director General of Indian Council of Agriculture Research (ICAR) Himanshu Pathak said that according to established research, one tonne of paddy requires 20 kilograms of nitrogen, 3.5 kilograms of phosphorus and 20 kilograms of potassium. India’s average per hectare yield of paddy is around 5 tonnes. This means that to get the optimum average yield, farmers require to apply 100 kgs of nitrogen, around 20 kgs of phosphorus and 100 kgs of potassium.

 

“Till the plants get this much quantity of nutrients, they won’t give the average yields,” Pathak told reporters on the sidelines of a press conference at the event.

 

Organic carbon present in soil can give around 40 kgs of nitrogen, which means the balance has to be supplemented from outside either through organic manure or chemical fertiliser.

 

Pathak said that 100 kgs of organic manure gives around 0.5-1 per cent of nitrogen. This means that to get the balance of 60 kgs of nitrogen, one needs to have 15-20 tonnes of organic manure per hectare.

 

SK Chaudhuri, DDG, Natural Resource Management at ICAR and chairman, organising committee of the Global Conference said that a mapping of India’s soil health has shown that almost 90 per cent of the land is deficient in nitrogen, 90 per cent in phosphorus and 50 per cent in potassium.

 

Meanwhile, agriculture minister Shivraj Singh Chouhan who also addressed the inaugural session of the global conference and expressed concern over soil degradation, affecting 30 per cent of India's land and stressed the need for urgent measures to maintain soil quality for sustainable farming.