Soil Fertility, SRI and Sustainability

Kishan Rao Parcha

SRI-System of Root Intensification

SRI

• In SRI, the roots of the plant, be it rice or wheat, spread wide and deep and efficiently metabolise nutrients, help tillering and give out strong stems and large leaves.

• In a non-chemical environment, the roots thrive and proliferate in the presence of ‘humus’ and friendly microbes.

Fertile Soils

About Depletion of NutrientsIt was vividly brought out in the deliberations that the

major factor responsible for the low anddeclining crop response to the fertilizers was the

continuous nutrient mining of the Indian soilswithout adequate replenishment to the desired extent. It

is estimated that about 28 Mt ofprimary plant nutrients are removed annually by crops in

India, while only 18 Mt or even less areapplied as fertilizer, leaving a net negative balance of

about 10 Mt of primary plant nutrients(NPK).

http://www.naasindia.org/Policy%20Papers/policy%2035.pdf

About Rice-Wheat Cropping Pattern

Of late, concerns have been expressedthat the rice-wheat growing areas are

developing a so-called “fatigue”, due tocontinuous uninterrupted cultivation of thisvery exhaustive cereal-cereal (rice-wheat)

cropping system, for now nearly threedecades. There is no doubt that rice andwheat, which have similar adventitious

rooting systems, are very heavy feeders ofplant nutrients.

‘SRI’ results in more depletion!(PSI farm, Dehradun, November 2006)

Variety Type 3SRI

Type 3SRI

PusaSugandhaTraditional

PusaSugandhaTraditional

PusaSugandha SRI

No of Hills 16 20 24 23 16No. of Total Tillers 189 146 158 210No of Grains perPanicle(Avg)

93 117 121 96 193

Total Weight(chaff+grain) gms

1800 3000 2000 2000 3500

Total Weight of Grains 450 460 390 720Net Weight of Grains gms 390 420 400 380 650Weight of unfilled grains 30 60 10 70

Weight of Chaff -gms 1410 2500 1540 1610 2780

Height of Chaff -cm 130 110 110 120 140

1 hectare=10,000 m2

1 m2 = 550 gm(Net Weight of Grains)= 5.5 Tonnes/Hectare; 2000 gm = 20 tonnes/hectare

‘swi’, going by the positive outcomes of PSI trials, also results

in even more depletion of remaining nutrients in the soil.

The Implications…..

•In the long run, the soil fertility goes down and along with that, the yields•The mineral deficiencies will make the plants/crop weak and disease prone•The food grains will be deficient in vital minerals and, in turn, affect the consumers’ health adversely•This rice-wheat cropping cycle, year after year, is unsustainable, be it SRI or traditional(organic) or traditional(chemical)

Then, what is the solution?

That is...

ReplenishmentThrough

Green Manure & CompostOr

Application of Macro & Micro Nutrients (Chemicals, in a balanced way)

The ‘Replenishment Doctrine’ is

* One crop for the Soil and

(only then)* One crop for Us

Is it practical/feasible?

Provided we find enough time and the ‘will’, for a

green-manure crop between

Rice & Wheat and, then,

Wheat & Rice

The Farmers and Scientists know that….

SOWING TIME: Under irrigated conditions, the first fortnight of November is considered to be the optimum time for sowing the medium long-duration wheats, e.g. 'kalyansona' all over India. For short-duration varieties, e.g. 'Sonalika', the second fortnight of November is the optimum time. In eastern India, the sowing of wheat is often delayed owing to the late harvesting of paddy. The sowings in such cases may go up to even the third week of December.http://www.krishiworld.com/html/field_crops2.html

And also…..

In north- western India also, wheat sowings get delayed due to late harvesting of paddy or sugarcane or potato. However, wheat sowings beyond the rain fed conditions, the second half of October is the optimum time. The sowing of wheat, when the temperatures are high results in a poor stand, poor tillering, attack by root-infecting fungi and pests and the early onset of flowering. All these factors depress yield. The success of rainfed wheat depends on the amount of conserved moisture in the soil.

Conclusion

If sustainable yields and nutritional security are to be achieved on a priority basis, we need to proactively intervene and cultivate green manure crops(preferably, Multi Variety Seed Sowing Technique) in between the two cereal crops, Rice & Wheat.The soils, presently, are on the brink of collapse all over the country.The present and future populations/generations would have some chance of survival only if the soils are restored, made healthy and fertile.

Thank You