Water-efficient sugarcane farming in Belgaum, Karnataka
A case study about a farmers innovative measures to produce no till sugarcane using water efficient, organic and alternate row methods of irrigation in Belgaum, Karnataka

Suresh Desai is a founding member of an Organic Farmers Club in Belgaum District of Karnataka, India. It has 400 members, some of whom are already growing crops organically, while others are in the process of shifting to organic farming.

Since completing his matriculation, Suresh has been caring for the family property of 4.5 hectares, in an area where today sugar cane is primarily grown. For nearly a decade Suresh, as the manager of the farm, followed conventional practices relying on external inputs in the form of chemical fertilizers and pesticides. Just like most of the other farmers near Belgaum, he grew sugar cane, a high water-demanding cash crop, and tobacco.

Conventionally, sugar cane is grown in three-year cycles. A sugar cane crop takes about 18 months to mature, it is then harvested and a ratoon crop is left to grow. After cutting the canes, a lot of trash remains in the fields. Some of this is used as a roofing material, while the rest is burnt, usually at night. Burning can damage the roots, but there is a good initial re-growth of the ratoon crop since the nutrients in the trash become soluble by burning. The burning also helps in pest control, ensuring that pest problems of the standing crop do not contaminate future cops. However, what most farmers do not realise is that most of the nutrients contained in the ashes are leached out with the first irrigation, and as the water demand of the sugar cane crop is high (recommendations are that it receives 100 percent water cover, effectively flooding the crop), this can be a serious problem. After the harvest of the ratoon crop, the field is left fallow until the next planting cycle which may be after six months or a year.

Suresh's yields for sugar cane were 75 to 90 tonnes a hectare, very much like that of his neighbours. However, Suresh started having second thoughts as he noticed a process of degradation unfolding in his fields. The crops became increasingly affected by pests and disease, the soil gradually lost its native fertility and structure, and water supplies were dwindling. In short, the family property was on the decline.

What most farmers do not realise is that most of the nutrients contained in the ashes are leached out with the first irrigation.

Initial experiments with organic practices

At that point it occurred to him that in fact there were plenty of residues available mainly from the sugar cane fields that were hitherto considered of no particular use. With the escalating prices for external inputs, Suresh began venturing into experiments that would ultimately bring a drastic change in the cultivation of his sugar cane fields. Suresh says that the driving factor for shifting away from chemical farming was economic. The understanding that organic materials were available and that the use of these could reverse the process of degradation of the family property pointed the way out.

At first he tried composting the residues and using this to fertilize his sugar cane crop. In this way he was able to reduce the inputs of chemical fertilizers to a certain extent, however, composting involved a lot of labour for collecting, mixing, watering, then turning and finally hauling the organic matter back to the fields to be ploughed in. Suresh reasoned that if the work of shifting organic matter to and from was avoided, it would mean a considerable saving in time and labour.

Suresh's system enables a reduction in water usage by 75 to 80 percent in comparison with the conventional usage.

This brought him to the next step wherein organic residues were incorporated in situ in the fields that produced them. With this method, Suresh was able to reduce the application of chemical fertilizers by 50 percent, while maintaining the same production levels. However, problems related to irrigation in heavy black cotton soils started to appear. Groundwater levels had declined drastically while the fields became slowly gorged with water and laden with salts. Suresh came to understand that irrigation itself was responsible for this slow but steady spoilage of the soils.

This brought him to the third change in his thinking and agricultural practice. He imagined that if the trash obtained after the cutting of the canes could be kept "on" the soil as mulch, evaporation losses would be significantly reduced, the need for irrigation would diminish and the salinization problem would eventually be overcome.

By keeping all the trash on the fields as mulch, Suresh found that irrigation became very difficult since the trash obstructs the flow of the irrigation water. The idea that the trash could be kept in one row and that the water could be provided in the next row became the solution to this problem. He calls this the "one-in-two" irrigation system. Moreover by connecting two parallel irrigation rows with a perpendicular trench at the ends, he made watering the fields much easier (see Figure below).

In one go Suresh Desai was able to reduce his irrigation requirement by 50 percent, and after harvesting the cane, the remaining trash was gathered in the row that was used previously as the irrigation channel.

Continuing in this way for three years, Suresh observed a remarkable improvement in the soil and an amazing increase in soil life. He also started using a soil conditioner and introducing green manure between the rows of cane and found that using chemical fertilizers became unnecessary. He also saw that his crops were healthy and that there was no more need for chemicals to combat pests and diseases. Furthermore, because of the intense soil life and the action it manifested on the soil, Suresh hazarded the idea that cultivation could perhaps be stopped altogether, so he did. His fields have not been ploughed or turned up for the last 5 years. The only soil work left is the periodic maintenance of the irrigation channels.

Zero tillage and reduced irrigation - the impacts achieved

Ever since ploughing was stopped, the water-retention capacity of the soil improved further. Consequently, irrigation frequency was reduced from once every 10 or 12 days to 20 or 25 days, thereby achieving a further saving of 50 percent in water requirement.

Suresh discovered that the cane crop thrived even when irrigation was further reduced to one in three rows. This meant yet another saving of 25 percent of water. Suresh is at present experimenting with pushing the lower limits of irrigation to one in four rows.

On the whole, Suresh's system enables a reduction in water usage by 75 to 80 percent in comparison with the conventional usage.

Soil fertility

Soil fertility in Suresh Desai's farm is maintained by the combined effect of four factors:

  • reduced irrigation;
  • trash composting;
  • green manuring;
  • soil conditioning.

Reduced irrigation: by reducing irrigation, salt build-up is minimized. It also restricts nutrient losses due to leaching. Soil compaction as a result of excessive irrigation is also avoided.

Trash composting: when trash is kept on the fields as mulch, evaporation of moisture is greatly reduced. The soil is protected from the direct impact of the elements and hence soil life develops extremely well. Soil quality and structure improve. Finally as the trash decomposes, nutrients are taken up by the roots again to make new growth.

Financial impacts

Suresh Desai has been able to drastically reduce his cash investment per hectare. This is mainly due to a 30 percent reduction in labour and reduced water requirement. The comparative figures are as follows:

Suresh Desai

in Rs

Others

in Rs

Cost of inputs per hectare

3 700

Cost of inputs per hectare

15 000

Yield 100 tonnes/hectare (at Rs 600/ton)

59 000

Yield 110 tonnes/hectare

66 000

Net profit

55 300

Net Profit

51 000

The use of traditional dry farming crops in his green manure mix functions as a gene pool for rapidly disappearing species.

These figures for Suresh Desai's investments, as well as other farmers, are averages. In some cases, in the conventional practice when farmers want to push their yields above 120 tons, the cost of inputs per acre can soar up to Rs 24 700 per hectare. Investments in the case of organic cultivation also increase if additional external inputs are used.

Posted by
Attachment
Get the latest news on water, straight to your inbox
Subscribe Now
Continue reading