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Mulching: Harvesting many benefits in cardamom

Intensive cultivation of cardamom, ignoring the traditional cultural practices, has resulted in repeated losses for cardamom farmers in the Western Ghats region. Paulose, an innovative farmer, has shown that by practising mulching, not only can the soil carbon content be improved, but better yields could be harvested on a sustainable basis.

Paulose showing fertile soil at plant base. Photo:Varadarasan

Paulose showing fertile soil at plant base. Photo:Varadarasan

Mulching increased the organic carbon content while lowering the soil acidity and the bulk density.

Small cardamom (Elettaria cardamomom) cultivation in the Western Ghats of southern India has largely contributed for minimizing the denudation of evergreen forest to a greater extent. Cardamom has been cultivated over a century in India with traditional methods. It has helped in preserving the serene western ghat ecosystem with least disturbance to soil and its microbial biodiversity.

However, intensive cultivation of cardamom in the recent past, has lead to crop loss due to diseases and pests attack, increased demand for labour and increased cost of cultivation.

Experimenting with new ideas

Mr.K.V.Paulose in Kajanapara village in Idukki district of Kerala, a cardamom grower is an innovative farmer who tries out new ideas in a small area on his farm before accepting or discarding them. He discarded many practices of using chemical inputs and slowly made progress towards ecofriendly and low cost cultural practices which reduced the cost of inputs in cardamom cultivation and maximized the yield.

Trees such as jackfruit, silver oak etc., were grown in cardamom plantation for providing shade. These trees are normally thinned or pruned before or on the onset of monsoon. But, Paulose pruned the trees during end of northeast monsoon, i.e. Dec – Jan, to minimize the damge caused to tillers by falling twigs / branches. Since the soil is fertile and heavily mulched, the roots are not exposed to extremes of temperature in summer months and hence plants are not affected. Instead, new shoots emerge in large numbers. The tall trees facilitate better aeration as well as allow copious indirect sun light fall on the tillers resulting in better photosynthesis and reduced canopy temperatures facilitating growth of tillers, better panicle, capsule and fruit set.

Measuring panicle length in cardamom plant. Photo: Varadarasan
Measuring panicle length in cardamom plant. Photo: Varadarasan

Mulching in cardamom

Paulose observed that those areas where soil is covered with fallen leaves of trees, the crop stand was good with less pest/ disease incidence. The fallen leaves and twigs is made into a thick cover of mulch over the soil. These leaves decompose by in-situ composting process.

The Indian Cardamom Research Institute (ICRI) studied the soil fertility on his farm and found that the organic carbon/humus content is higher in his garden compared to neighboring plantation. The soil bulk density is also very low. Mulching reduced the acidity of the soil and increased the organic carbon content. With increased carbon content, Paulose restricted the application of chemical fertilizers to single application. Usually farmers in the region apply 4 -7 rounds of fertilizer application.

It was observed that mulching resulted in several advantages – the plant growth is healthy and the damage due to thrips on capsules and stem borer is negligible; the height of the 17 year old plant is 15 – 20 feet tall and there are about 100 tillers in each clump. Usually cardamom fields are replanted with new suckers in 8-10 years of cultivation. But Paulose has retained the plantation successfully for 17 years with compact clumps. The old suckers decompose faster instead of rotting, which is also due to reduced soil acidity. Lateral roots are noticed even in the interspaces. There is no need for weeding as the soil is not exposed and self shade of cardamom clumps discourages weed growth.

Reaping several benefits

By practicing mulching and other soil fertility enhancement practices, Paulose was successful in harvesting better yields. On an average he harvests about 2 – 5 kg of dried cardamom / clump (of 100 tillers). The size of fruits (capsules) are bold and round in shape and the seeds are bold (dry capsule liter weight is 420- 460 g). Seed weight percentage is more than 83! He was awarded first prize by Spices Board for getting highest yield of cardamom during 1995 and 2009- 2010.

Other benefits included lesser costs of cultivation as labour costs reduced owing to no weeding. The costs also reduced as minimum external inputs were applied. Also, with lesser use of chemicals, the natural enemies of pests, particularly the shoot borer, was very high. A survey conducted in August 2012 revealed that there was 47% parasitization in his plot as compared to 12% in ICRI farm and 2% in a farmers plot, where more insecticides are used. This also encouraged colonization of honey bees which helped in enhanced pollination.

Paulose is now a role model to many in ecofriendly cultivation of cardamom with low investment. Several farmers visit Paulose farm to learn the methods he has been following.

S Varadarasan and P Vivekanandan

S Varadarasan, Former Scientist, ICRI
Myladumpara, Idukki district, Kerala
E-mail:shanvarad@gmail.com

P Vivekanandan, Executive Director, SEVA
45 TPM Nagar, Viratipattu, Madurai-16