Rainwater management

1 Rain-water management for teak (Tectona grandis Linn, f.), mango (Mangifera indica Linn.) and neem (Azadirachta indica A. Juss) in arid and semi-arid regions

Description of the ITK

This practice is to retain rain water in the soil and to grow trees, particularly mango, neem and teak, which are best suited for arid and semi-arid regions. The practice is appropriate for a garden or estate where teak, mango or neem trees are grown. This technique may be adopted in areas where there is less water available. There is no practical risk and it is easy to handle, less labour intensive and best suited for such trees. This is in practice in Periakovilankullam village of Tirunelveli district in Tamil Nadu.

Name and address of the discloser

Thiru S. Murugesan, Periakovilankulam, Sankararkovil, Tirunelveli district, Tamil Nadu 627 953.

Location of use of the ITK

Periakovilankulam, Sankararkovil (P.O.), Tirunelveli district (Tamil Nadu) 627 953.

Experimenters

Dr. S.V.K Hiswaran, Associate Professor, Forest College and Research Institute, Mettupalayam, Coimbatore 641 301 (Tamil Nadu), Dr. G. Subba Reddy, Head, Division of Crop Sciences, Dr. N.N. Reddy, Senior Scientist (Horticulture), Central Research Institute for Dryland Agriculture, Hyderabad 500 059 (Andhra Pradesh).

Results and discussion

An unstructured interview was conducted to obtain the details of the ITK prior to conducting the experiment. The experiment was laid out at Forest Research College, Mettupalayam (Tamil Nadu) for 3 years (2002-2004) for trees of teak, mango and neem to assess the effect of soil moisture-conservation practices by making micro-depressions around the basin of the plant (ITK method). This was compared with the conventional basin method for the first and second years. As a part of cross validation, the experiments were conducted at Central Research Institute for Dryland Agriculture (CRIDA), Hyderabad with grass mulch in 3 years old trees of mango and teak during third year 2004.

Moisture content in soil

More moisture was retained in the treatments under teak and neem compared with the treatments in mango. The moisture content was maximum at 60 cm depth in both the treatments throughout the period. With increase in soil depth from 15 to 60 cm, soil-moisture retention increased.

Biometric observations

It is evident that the growth of trees was faster in the method of micro-depressions over the other treatments and the difference was still obvious with pebble mulch during summer.

Soil analysis

Available nitrogen and potassium content in soil was not influenced by the treatments. However, available phosphorus content (20.3 kg/ ha) was higher in the treatment of micro-depression than in the basins (15.7 kg/ha). The growth of teak and mango at Mettupalayam and Hyderabad indicate that while micro-depression favoured growth of the trees at Mettupalayam, it had no impact on tree growth at Hyderabad.

Treatments in mango recorded lower percentage of soil-moisture retention, which might be due to the variation in the distance of micro-depressions made. High rainfall intensities lead to filling of the microdepressions with soil and all the treatments would be at par with each other at this condition, whereas microdepressions (ITK) were helpful in retaining more moisture during low-intensity rain-fall periods and helped avoid death of trees due to continuous droughts.

Conclusion

The advantage of the micro-depressions method is that it can retain the soil transported by erosion in the run-off water, by collecting in the micro-depressions. The micro-depression method has been found to intercept more run-off water compared with basin method. This method has been found to be useful where trees are grown under rainfed conditions. Soil fertility tends to improve in plots where microdepressions were made at Mettupalayam.

2 Rain-water measurement using rolu (indigenous raingauge)

Description of the ITK

Rolu (7.4” depth, 9” diameter hole on a 3’x3’x1.5’ granite stone block) is useful in knowing the quantity of rainfall for sowing. Seeds in the field are sown when the rolu is filled with rain-water. This technique helps the farmers in estimating the rainfall that is sufficient to go for seeding. This method is adopted for sowing dryland crops like sorghum, castor etc. in Alfisols.

Name and address of the discloser

Shri Narasimha Reddy, Nallavelli, Yacharam mandal, Ranga Reddy dist., Andhra Pradesh.

Location of use of the ITK

Nallavelli village, Yacharam mandal, Ranga Reddy dist., Andhra Pradesh.

Experimenters

Dr. V. Maruthi, Senior Scientist (Agronomy), Dr. G. Subba Reddy, Head, Division of Crop Sciences and Shri N.N.Srivastava, Principal Scientist (Agrometeorology), Central Research Institute for Dryland Agriculture, Hyderabad, Andhra Pradesh 500 059.

Results and discussion

Experimental validation was done under both on-station (CRIDA Research Farms at Gunegal and Hayathnagar) and on-farm situations in the villages of Nallavelli, Nasdik Singaram of Ranga Reddy district and Gollapalli village of Nalgonda district during rainy (kharif) season. The rainfall from both indigenous and standard rain-gauges established at different experimental sites was recorded during rain events during July-October 2002-04. Simultaneously, the various agricultural operations done by the farmers were related with the rainfall received during growing season of crops such as sorghum + pigeon pea, castor etc.

Operations performed in relation to depth of rain water received in indigenous rain-gauge

On-station trial

Sorghum + pigeonpea were sown by 50-100% farmers in 3 days when the indigenous rain-gauge was filled to >3/4 capacity or more in the research station. Castor was sown for 1-3 days when the indigenous rain-gauge was up to >3/4 capacity, leading to 100% sowings.

On-farm trials

Sorghum+ pigeonpea were sown in 2-7 days by the farmers, leading to 100% sowings with rain-water filling to 1/2—>3/4th capacity of the indigenous raingauge. In Nallavelli of Yacharam mandal of Ranga Reddy district of Andhra Pradesh, it was recorded that when the rainfall received in indigenous raingauge ranged from 1/2 to full, which was about 8-33 mm in standard rain-gauge, it resulted in 100% sowing of sorghum + pigeon pea crops in the farmers’ fields. It was observed that the rainfall received in indigenous rain-gauge when corrected was nearer to the recorded rainfall of standard rain-gauge.

Conclusion

When the indigenous rain-gauge was full, sorghum + pigeon pea were sown by all the farmers within 3 days, which technically amounts to 50 mm in the standard rain-gauge. Sowings can be continued for 2 more days. With this, it fulfils the claim made by the discloser. But the claim gets vitiated under delayed monsoon conditions, because the season to sow sorghum + pigeon pea would be lost for the fear of sorghum shootfly attack, and the farmer will prefer to sow castor instead of sorghum + pigeon pea. Low price of the indigenous rain-gauge made of granite ranging from Rs. 250 to 300, which can be made by the local mason, and its less proneness to theft over the standard rain-gauge are the major advantages.

3 Method of rain-water management in mountainous land scape under apple orchard

Description of the ITK

In several parts of the Himalayas villages, villagers often harvest rain water by building small waterstorage “ponds” (locally called chaal).The number of such ponds varies from 30 to 40 depending upon the valleys and villages. Each water pond is 9 m. long, 9 m. wide and 0.9 m deep. The water used as drinking water for cattle and for irrigation purposes.

Name and address of the discloser

Shri Prem Singh Verma, Gawahi village, Sandhu P.O., Theog tehsil, Shimla (Himachal Pradesh) 171 222.

Location of use of the ITK

Different villages in the foot-hills or valleys of the Himalayas were considered. The experimental site is an apple orchard, located at village Gawahi, which is 45 km from Shimla city on national highway 22 (commonly called Hindustan-Tibet Road) and 8 km from Theog town, which is a gateway to apple belt of Shimla district. The orchard is of about 3 ha area, at 2,400 m above MSL, which was established 10 years ago.

Experimenters

Dr. Pradeep K. Sharma, Chief Scientist (WM), Dr. O.C. Kapur, Senior Scientist (Soils), and Dr. S. S. Masand, Senior Scientist (Soils), Department of Soil Science, Ch. Sarwan Kumar Krishi Viswa Vidyalaya, Palampur (Himachal Pradesh) 176 062.

Results and discussion

This experiment was conducted during 2002- 2004. Two sets of treatments were imposed in this study.

  1. For in-situ rain-water harvesting and profile moisture conservation, the following three sets of treatments, in addition to control, were tested: mulching, terracing + mulching, and terracing + trenching + mulching.
  2. For testing chaal, five types of dug-out tanks were constructed at appropriate locations in the experimental area, viz. (i) polyethelene-lined tank, (ii) bitumen (tarcoal)-lined tank, (iii) cement+ concrete lined tank (RCC), (iv) mudplastered tank, and (v) unlined tank (control).

The whole experimental site was divided into three blocks for imposing the following treatments:

  1. Terracing: Land shaping between two apple trees along the contours in such a way that rain water flows towards the tree basins,
  2. Trenching: Small trenches of appropriate sizes were dug above the tree basins to harvest rain water in situ.
  3. Mulching: The tree basins were mulched with FYM, pine-needles, pebbles and cocopit, in addition to unmulched control.

Stability of terraces and trenches

Land shaping (trenching and terracing) was done in October-November 2002. Due to fragile nature of landscape and heavy snowfall during winters, the terracing was severely damaged, and had to be reconstructed after one and half years. Therefore trenches need to be frequently repaired in fragile and erosion-prone soils. In spite of the damage done to the terraces and trenches due to rainfall and snow, the moisture conservation due to these land-shaping treatments encouraged the growth of natural vegetation. After the rainy season, the terraces provided with trenches showed profuse growth of grasses and leguminous vines due to profile water conservation. It would help in soil conservation and add organic matter to the soil upon its decay.

Soil-moisture conservation

Land shaping had significant effect on soilmoisture conservation. Soil moisture in all soil layers and at all dates was significantly higher in plant basins terracing and trenching. Trenching enhanced water conservation through harvesting the runoff water and the water directly from the rains and snow. Terracing alone was also effective in conserving moisture by directing the flow of runoff towards plant basins. Terracing and trenching thus should be practised in rainfed orchards for harvesting and conserving rain water in situ. Mulching retained more soil moisture than no-mulch. Pine-needle mulch had an edge over other mulch materials. Pine needles are easily available locally. Pebbles also appear as a potential mulch material, as they are also locally available in plenty. The land shaping as well as mulching used for soil-moisture conservation significantly improved the growth parameters of apple trees, viz. plant height, canopy circumference and stem diameter.

The making of tree basins significantly improved all the three growth parameters. However, composition of terracing and trenching further improved the plant growth whereas all the three parameters were highest under the treatment of basin+terrace+trenching. Likewise, growth of apple trees was better with mulch than without mulch and highest plant growth was observed with pine-needle mulch.

Effect of mulching on water status of apple Trees

The relative leaf water content (RLWC) increased significantly with the application of mulch. Highest RLWC was observed with pine-needle mulch, and the lowest in control.

Water harvesting

The RCC and polylined tanks were effective in storing rain water in-situ water from springs brought to the site through rubber pipes. No seepage was observed in RCC and polylined tanks even after 2 years of their construction. The bitumen-lined tank did not perform well at this site, because the soil at the experimental site was loose and gravelly. The chaal has to be lined with some effective sealant, like RCC or polyethylene (UV resistant material).

Cost of construction was highest in RCC tank, followed by polylining and bitumen lining. Although the cost involved in the construction of mud-plastered and un-lined tanks was minimum, their utility would depend on the seepage losses and hence the effective water storage. Chaals without lining are not effective at all locations because of excessive seepage losses. To increase their efficiency in storing the harvested rain water, either the chaals have to be lined with suitable lining materials, or locations have to be identified for constructing chaals, that are low lying and naturally have very low permeability to water. Polythelene and RCC were two very effective lining materials for checking seepage losses in chaals. Since RCC is very expensive, polythelene is recommended to check seepage losses from each tank.

Conclusion

These studies have shown that chaal is an effective structure for harvesting water from lining material. Bitumen, being hydrophobic in nature, is also effective in reducing seepage losses from farm ponds, but its mode of application needs to be standardized in loose and gravelly soils. Land shaping (terracing and trenching) was very effective in conserving soil moisture in tree basins by directing the run-off water towards tree basins and harvesting the rain water. The moisture conservation effect was further enhanced when land shaping was coupled with mulching and observed significant growth of apple trees. Pineneedle mulch was comparatively more effective in moisture conservation. The pebble mulch was also effective, and may be easy to apply at on farm level because of its easy availability locally. However, due to fragile nature of the land scape, the terracing and trenches were damaged due to snowfall and rains, and had to be repaired even after 1 year of construction.

Reference

Traditional Knowledge in Agriculture

Division of Agricultural Extension
Indian Council of Agricultural Research
New Delhi – 110012

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