Patchy rains, delayed sowing: How uneven rainfall is affecting farms

Despite recent heavy rainfall, cumulative monsoon deficits remain. Here's why the timing and distribution of rain matter as much as seasonal totals for agriculture

Episodes of extremely heavy rainfall have dominated headlines over the past fortnight, with parts of Gujarat and Odisha receiving more than 30 cm of rain in a day. Yet, the southwest monsoon has remained below normal since June.

 

Data from the India Meteorological Department (IMD) shows that while rainfall improved in the third week of July, cumulative rainfall across the country was still 19 per cent below the long-period average (LPA) as of July 22.

 

The pattern has triggered discussion about whether the distribution of rainfall matters as much as, or even more than, the seasonal total.

How has the monsoon fared so far?

The IMD's latest extended-range forecast shows rainfall during the week of July 16-22 was nearly normal across the country, at 1 per cent below the LPA.

 

 

Central India recorded 10 per cent above-normal rainfall during the week, while northwest India received 5 per cent above-normal rainfall. East and Northeast India remained 10 per cent below normal, while the South Peninsula recorded a deficit of 26 per cent.

 

The seasonal picture, however, remained weaker.

 

Between June 1 and July 22, India received 293.3 mm of rainfall against the normal 361.5 mm, which left the country with a deficit of 19 per cent.

 

East and Northeast India recorded the biggest shortfall at 32 per cent below normal, followed by the South Peninsula at 26 per cent below normal. Northwest India remained 13 per cent below normal, while Central India recorded a deficit of 9 per cent.

 

The data suggests that rainfall activity has strengthened in recent weeks but has not fully offset the deficits accumulated earlier in the season.

How has rainfall varied across regions?

Over the past few days, rainfall has been concentrated in several pockets as successive weather systems developed over the Bay of Bengal and western India.

 

On July 25, the IMD reported exceptionally heavy rainfall over Gujarat, with Santalpur in Patan district recording 39 cm in 24 hours. Very heavy rainfall was also recorded in parts of Madhya Maharashtra, Saurashtra and Kutch, Jharkhand and Odisha.

 

A day later, Jagatsinghpur in Odisha recorded 33 cm of rainfall, while parts of Chhattisgarh, Konkan, Madhya Maharashtra, Gujarat and Coastal Karnataka also received very heavy rainfall. The IMD said a depression over the northwest Bay of Bengal was expected to intensify further before crossing the Odisha-West Bengal coast.

 

According to Ram Prasad Lal, a retired Scientist-E from the IMD, such variations are not unusual during the southwest monsoon.

 

"Basic fact about the monsoon rain is that it occurs in a pulsating manner as the system advances. Therefore, there is always spatial variability in rainfall with time and space," Lal told Business Standard.

 

He added that rainfall patterns also depend on the type of weather system. A normal monsoon wave generally produces lighter rainfall over a wider area, whereas cyclones and depressions bring heavy rainfall along relatively narrow tracks.

 

Lal also said that the rainfall figures reported by the IMD are area-weighted averages and that uneven spatial distribution can result in lower rainfall over larger areas despite intense rain in isolated locations. He added that long-range forecasts indicate the probability of rainfall and should not be interpreted as forecasts of patchy rainfall.

 

"Patchy rains are normal phenomenon in monsoon rains and all tropical area," Lal said.

What does the forecast suggest?

The IMD expects rainfall activity to continue over the coming fortnight, although regional differences are likely to persist.

 

For the week ending July 29, the department has forecast above-normal rainfall over much of western and central India and many parts of eastern India, while rainfall is expected to remain below normal over the remaining parts of the country.

 

Heavy to very heavy rainfall is likely over parts of Rajasthan, Gujarat, Konkan, Madhya Maharashtra, the Western Himalayan region and the Northeast.

 

For the following week, from July 30 to August 5, rainfall across the country is expected to remain near normal overall. However, the IMD has forecast below-normal rainfall over several regions even during that period, indicating that rainfall distribution is unlikely to be uniform.

Why does patchy rainfall matter for agriculture?

An agronomist said crops respond to the timing and distribution of rainfall rather than the seasonal total alone.

 

"Crops need water at specific growth stages, not just a total amount over the season," said Dr Sandeep Menon, Professor and Head, Department of Agronomy at Lovely Professional University.

 

He said prolonged dry spells followed by intense rainfall can result in poor and staggered germination, shallow root development and moisture stress during flowering or grain filling. Heavy rainfall can also lead to waterlogging and nutrient loss. By contrast, evenly distributed rainfall allows crops to develop stronger root systems and maintain soil moisture needed for nutrient uptake.

 

Menon said a spell of intense rainfall cannot fully compensate for several weeks of deficient rainfall.

 

"It can refill topsoil moisture and recharge groundwater, and it can rescue a sowing window if the crop hasn't failed yet. But it can't undo damage already done like poor germination, stunted early roots, or a missed flowering-stage watering," he said. Much of the rainfall from an intense downpour also runs off or causes waterlogging instead of reaching the crop root zone, he added.

 

He said pulses, soybean, groundnut, maize and cotton are among the crops most vulnerable to alternating dry spells and heavy rainfall, while transplanted rice can tolerate heavy rainfall better but suffers if delayed rains affect nursery preparation or transplanting.

 

The uneven rainfall pattern may also influence farmers' decisions during the sowing season.

 

According to Menon, farmers may delay sowing, switch to shorter-duration or drought-tolerant varieties, or reduce the sown area in response to early-season dry spells.

 

Even if seasonal rainfall eventually reaches normal levels, those decisions can limit yield potential because the optimal sowing window may already have passed.

 

Recent agriculture ministry data showcases that trend. As of July 24, kharif sowing covered 78.7 million hectares, compared with 82.6 million hectares during the same period last year, although the gap has narrowed as rainfall improved across several regions.

Can August improve the outlook?

Menon said improved rainfall in August can still support crops that were sown on time and are approaching flowering, while also replenishing soil moisture, reservoirs and groundwater.

 

However, he said recovery has limits.

 

"Sowing area lost in the optimal June-early July window is largely gone," he said. Crops that experienced stress during germination or early vegetative growth are also likely to carry a lasting yield penalty even if rainfall improves later in the season.

 

Rainfall has become more active over the past fortnight, and more rain is forecast over the coming weeks. At the same time, cumulative deficits remain across several regions, while agriculture will depend not only on how much rain falls during the rest of the season, but also on where and when it arrives.