Higher Groundnut Yield in India with Potassium

Groundnut farmers in the east of India have been given some compelling evidence of how choosing and using the right strategy with potassium fertilizer generates as much as a 30% increase in the yield of these delicious and nutritious kernels.

A Highly Important Crop with Low Performance

Of the nine important oilseeds crops grown in India, groundnut is the most important. Groundnut contains up to 55% oil and 28% protein. It is a tasty, versatile and, not surprisingly, very popular food for rural and urban Indians alike.

The state of Gujarat is ranked first in the league table of groundnut-producing Indian states, however, wherever groundnuts are grown, they often yield well below their potential. The low productivity is due to a whole host of factors including shortage of rainfall, inadequate crop rotation, and growing the crop on poorer, or marginal, land.

Odisha, a coastal state in the east of India, is another important groundnut producing region. The problems holding back productivity there include high soil acidity together with low and unbalanced fertilizer use. In fact, the crop often fails altogether due to low soil moisture and disease.

A team from Orissa University of Agriculture and Technology in Odisha (with financial support from the International Potash Institute (IPI), Switzerland) thought that better yields might be possible, particularly if the farmers’ use of potassium fertilizer could be better understood and modified. They set about investigating what would happen if the amount and frequency of potassium fertilizer applied was increased.

Role of Potassium in Groundnut

As with many crops, potassium is an essential nutrient. It is involved in most of the processes that influence plant growth. It significantly affects development – particularly root establishment – and day-to-day functions including water and nutrient uptake and carbon exchange. Not only all that, but potassium also helps plants cope with stress from diseases, pests, drought, salinity, cold, frost, and even water-logging. This makes it crucial to plant health, growth, and productivity to have the right amount of potassium at the right time.

Right Amount and Right Time for Potassium and Groundnuts

The research team aimed to determine the appropriate potassium dose for rabi (winter) groundnuts in Odisha, to compare the difference between applying potassium just once (a basal application before planting) or splitting the dose into two applications (basal and at flowering). They also wanted to establish a recommendation that farmers could understand and use with success.

The agronomy research farm of the College of Agriculture at the Orissa University of Agriculture and Technology in Odisha was host to the experiment. The site has a sandy loam soil, is slightly acidic, medium in organic carbon, low in available nitrogen and low in available potassium oxide. These characteristics closely match those of the fields of many groundnut farmers in the region. They also have a shared sub-tropical climate with a hot and humid summer (March-June), hot and wet monsoon (late June to mid-October), and a mild, dry winter (November to February). The weather restricts groundnut cultivation to the period from December to June.

The groundnut potassium fertilizer experiment comprised eight treatments, replicated three times in a randomized block design, using a popular ground nut variety known as Devi. The blocks of groundnut were treated with different doses of fertilizer as shown in Table 1. The first or basal dose of fertilizer, which included the usual recommended mix of nutrients such as nitrogen, phosphorus, and potassium, was placed in furrows at the time of sowing. Subsequent splits of potassium fertilizer, from the equivalent of 40 to 80 kg K₂0/ha, were placed beside the rows of groundnuts at the required number of days after sowing.

Table 1. A detailed description of the fertilization treatments with nitrogen (N), phosphorus (P) and potassium (K) and days after sowing (DAS).

As the crop developed, the researchers carefully monitored the crop to measure indicators of effects such as drought damage, plant processes and water stress. When the crop was mature, five plants were randomly selected from the middle of each plot, sun-dried, weighed and the pod yield was calculated per hectare. A 1 kg sample of pods was shelled, and the shells and kernels were measured to determine the number and weight of kernels from each plot and treatment.

How to Optimize Potassium

The results of the experiment in Odisha confirmed results from earlier investigations, that increasing the overall potassium fertilizer dose for groundnuts, and splitting it into two applications, increases yield. In fact, the enhanced fertilizer strategy brought about a significant 30% increase in yield of groundnut.

The work showed that elevating the recommended potassium dose from 40 to 80 kg K₂O/ha had marked agronomic benefits to the crop. This is probably because having adequate potassium was beneficial to the use efficiency of other nutrients such as nitrogen and potash, particularly in the early stage of growth when root establishment is key.

However, the capacity of the young crop to take up the whole seasonal potassium dose is limited. Much of the potassium applied may be lost through leaching or fixation in the soil and therefore not be available for uptake at later stages in crop growth when demand for potassium surges. That is why splitting the potassium application into two, at planting and flowering, in this experiment and others, is shown to be so effective for enhancing groundnut nutrition and productivity.

Figure showing effect of different fertilization treatments on groundnut yield. See Table 1 for treatment details.

As is so often the case with research work, the results give rise to even more questions about the what the upper limit is for potassium dosage before yield flatlines. There will, no doubt, be more investigations – and results.

In the meantime, the significant benefits of providing potassium fertilizer in the right amounts, and at the right time, is clearer than ever for groundnut farmers in Odisha, India.

More information

For more information about this research see the full report in the e-ifc published by the International Potash Institute (IPI).