Irrigation and Soil Moisture Conservation Strategies for Mulberry Cultivation

Mulberry is a water-sensitive crop. Too little moisture and the leaves shrink, lose protein, and become unfit for silkworm rearing. Too much water and the roots rot. For farmers in eastern and north-eastern India-where monsoons drench the land for months and dry spells follow-getting irrigation, moisture conservation, and weeding right is what separates a productive plantation from a failing one. This post breaks down the practical strategies for each.

Why water management matters in mulberry 🔗

Mulberry is the sole food source for the silkworm Bombyx mori, and leaf quality depends directly on consistent soil moisture. A mulberry plantation typically needs about 50-60 mm of water per week during active growth. Under irrigated conditions, this means watering at regular intervals-usually every 10-15 days depending on the soil type. Loamy soils dry out faster and need irrigation roughly every 10 days, while clayey soils with better water-holding capacity can go up to 15 days between irrigations.

In the eastern and north-eastern regions of India-covering states like West Bengal, Assam, Meghalaya, and Manipur-rainfall can be heavy during the monsoon (June to September) but drops sharply afterwards. This seasonal imbalance makes it essential to plan irrigation for the dry months while managing excess water during the rains.

Irrigation methods for mulberry plantations 🔗

The right irrigation method depends on plantation size, water availability, terrain, and budget. Here are the main options used across India for mulberry cultivation.

Basin irrigation 🔗

This is the most widely used method, especially for small to medium plantations. Small depressions are created around each plant to hold water. For young saplings, basins of about 30-60 cm diameter work well; they can be expanded as the plant grows. Basin irrigation concentrates water exactly at the root zone, reducing wastage from runoff. It is particularly useful in areas where water supply is limited.

Furrow irrigation 🔗

When mulberry is planted in rows, furrow irrigation allows farmers to water multiple plants simultaneously by channelling water through shallow trenches between the rows. It works best on flat or gently sloping land and is more efficient than flood irrigation for row-planted gardens. According to researchers at Indian agricultural universities, furrow and flat bed methods are among the standard techniques recommended for mulberry in North and East India.

Drip irrigation 🔗

Drip irrigation delivers water directly to the root zone through a network of tubes and emitters. It is the most water-efficient method, saving up to 40% of water compared to surface irrigation methods. Though the initial setup cost is higher, drip systems are ideal for areas facing water scarcity or for larger commercial plantations. They also reduce weed growth in non-irrigated inter-row spaces since water is applied only near the plant base.

Sprinkler irrigation 🔗

Overhead sprinklers simulate rainfall and can cover large areas uniformly. They are useful in undulating or hilly terrains of north-eastern India where surface methods are impractical. However, sprinklers are less water-efficient than drip systems and may promote foliar diseases if used excessively.

Irrigation scheduling by growth stage 🔗

Mulberry’s water needs change as the plant matures. Getting the timing right at each stage prevents both water stress and wastage.

Establishment phase (first 3-6 months) 🔗

Newly planted cuttings or saplings need frequent, light watering to help roots establish. Watering every 3-5 days in the absence of rain is recommended. The Central Silk Board recommends watering saplings immediately after transplanting and continuing regular irrigation as needed during this phase.

Active growth phase 🔗

Once established, mulberry plants enter rapid growth. During this stage, deep but less frequent irrigation-every 7-15 days-encourages roots to grow deeper, making the plant more drought-resistant in the long run. In South India, the recommended interval is about 10 days; in North and East India, it is often 7 days during the peak growing season.

Pre-harvest and harvest phase 🔗

Consistent moisture during the weeks before leaf harvest is critical. Water stress at this stage reduces leaf size, moisture content, and protein levels-all of which directly affect silkworm rearing outcomes. Avoid irregular watering cycles during this period.

Soil moisture conservation in rainfed and hilly regions 🔗

Not all mulberry-growing areas have access to reliable irrigation. Across much of eastern and north-eastern India-particularly in the hilly tracts of Meghalaya, Manipur, and parts of Assam-farmers depend largely on rainwater. Here, conserving whatever moisture the soil receives becomes the central strategy.

Mulching 🔗

Mulching is arguably the single most effective moisture conservation practice for mulberry. It involves covering the soil surface around plants with organic or inorganic material to reduce evaporation, moderate soil temperature, and suppress weeds-all at once.

Organic mulches such as dried leaves, rice straw, grass clippings, or mulberry pruning waste are most commonly used. A layer of about 8-10 cm thick, spread from the plant base to the canopy’s drip line, works well. As organic mulch decomposes, it also adds nutrients back to the soil. Research published in the Journal of Agriculture and Environment for International Development found that organic mulching with sunn hemp in rainfed lateritic soils of West Bengal significantly improved moisture retention and enhanced mulberry leaf yield and quality.

Black polythene mulching is another option that has shown strong results. A study on black polythene mulching in mulberry gardens reported over 50% increase in soil moisture content and nearly 58% increase in leaf yield compared to unmulched plots. It also achieved over 97% weed control efficiency. However, polythene is not biodegradable, so disposal must be planned carefully.

Research from Frontiers in Agronomy confirms that mulching serves as a protective barrier that absorbs rainwater, slows runoff, and reduces erosion-benefits that are especially valuable on sloping terrain in hilly regions.

Basin preparation and compartmental bunding 🔗

In hilly and sloping areas, creating basins around individual plants or building small compartmental bunds across the field helps trap rainwater where it falls. Instead of running off downhill, water infiltrates into the soil near the roots. This technique is low-cost and can be done manually using basic farm tools. Contour bunding-building bunds along the natural contours of a slope-is particularly effective for larger plantations on undulating terrain.

Green manuring 🔗

Growing short-duration leguminous crops like sunn hemp (Crotalaria juncea), dhaincha, or cowpea between mulberry rows and ploughing them into the soil before they flower serves a dual purpose. It adds organic matter that improves the soil’s water-holding capacity, and the root channels left behind help with rainwater infiltration. The FAO recommends incorporating green manure crops like horse gram, cowpea, or sunn hemp into mulberry gardens before the end of the monsoon season.

Fall ploughing 🔗

Deep ploughing of the field after the monsoon season breaks up compacted soil layers and creates channels for moisture to move deeper into the soil profile. This stored subsoil moisture then becomes available to mulberry roots during the subsequent dry season.

Seasonal moisture management calendar 🔗

Effective moisture management in eastern and north-eastern India follows the seasonal cycle closely.

Pre-monsoon (March-May): This is the time to apply mulch, repair bunds, and complete weeding before the rains arrive. If irrigation is available, water every 7-10 days to maintain growth during the hottest months.

Monsoon (June-September): Focus shifts from irrigation to drainage. Waterlogging is the main risk. Ensure that drainage channels around the plantation are clear. Use this period to establish green manure crops and refresh organic mulches.

Post-monsoon (October-February): This is when stored moisture becomes most critical. Mulches applied earlier now pay off by retaining residual soil moisture. Supplement with irrigation if available-every 10-15 days depending on soil type and remaining moisture levels.

Weeding: the often overlooked competitor 🔗

Weeds are direct competitors to mulberry for water, nutrients, and sunlight. In a crop that is grown as a monoculture with regular fertiliser applications and wide spacing, conditions are ideal for aggressive weed growth. According to a comprehensive review in Agricultural Reviews, weeds cause 30-40% losses in mulberry leaf yield. Reducing this weed-related loss by even half could boost leaf production by 9-12 metric tonnes per hectare per year-enough to produce significantly more raw silk.

Common weeds in mulberry gardens 🔗

The weed flora in mulberry fields varies by region and soil type. Across India, 57 to 141 weed species from 28-44 families have been reported in mulberry plantations. Some of the most problematic ones include Cynodon dactylon (Bermuda grass or Hariyali), Cyperus rotundus (nut grass), and various broadleaf annuals. These weeds establish quickly after pruning or harvest, competing aggressively just when mulberry plants are trying to regrow.

Manual weeding 🔗

Hand weeding is the oldest and most widely practised method in Indian mulberry gardens. It involves pulling weeds out by hand or using hand hoes and sickles. It is most effective when done while the soil is moist, as roots come out more completely. A typical mulberry plantation needs weeding at least 3-4 times a year. The first weeding should be done about two months after planting, followed by a second round two to three months later. After that, weeding after every pruning or harvest cycle is standard practice.

The main drawback of manual weeding is the high labour cost and time involved. This is a growing concern in eastern and north-eastern India, where agricultural labour availability has been declining.

Mechanical weeding 🔗

Using hoes, cultivators, or wheel-mounted weeders can speed up the process in larger plantations. However, care must be taken to keep cultivation shallow-mulberry has lateral feeder roots that can be damaged by deep tillage. Light surface hoeing that cuts weeds just below ground level is usually the safest approach.

Chemical weed control 🔗

Herbicides can be effective in the early stages after pruning. Pre-emergence herbicides keep the plantation weed-free during the first few weeks of regrowth. However, there is a critical limitation: once mulberry leaves start developing (typically 30 days after pruning), herbicide use must stop. Any chemical residue on the leaves can be toxic to silkworms. This makes herbicides useful only as a supplementary tool, not a standalone solution.

Mulching for weed suppression 🔗

As discussed in the moisture conservation section, mulching does double duty. A thick mulch layer blocks sunlight from reaching weed seeds, preventing them from germinating. Black polythene mulch is especially effective for this purpose, achieving over 93% weed control efficiency in trials.

Intercropping for weed management 🔗

Planting short-duration pulse crops like black gram, green gram, or cowpea between mulberry rows during the early stages of plantation establishment can suppress weeds by covering the ground and competing with weed seedlings. These intercrops also fix nitrogen in the soil, improving fertility. Once the mulberry canopy closes, intercrops are no longer necessary as the shade naturally reduces weed growth.

Integrated weed management 🔗

No single weeding method is sufficient on its own. The most effective approach combines multiple strategies: pre-emergence herbicide application immediately after pruning, followed by manual weeding once the leaf canopy develops, supplemented by mulching or cover cropping. This integrated method reduces reliance on any one technique, lowers overall cost, and avoids the risk of herbicide residue affecting silkworm health.

How irrigation, moisture conservation, and weeding connect 🔗

These three practices are deeply interconnected. Poor irrigation management leads to dry, stressed plants that lose their competitive edge against weeds. Unchecked weed growth absorbs soil moisture that should be going to mulberry roots, effectively undoing the benefits of irrigation. And without moisture conservation measures, even well-irrigated plantations waste water to evaporation and runoff.

The practical takeaway is to plan all three together. Apply mulch after pruning (conserves moisture and suppresses weeds). Time your weeding to happen before mulch application. Schedule irrigation based on soil moisture levels rather than a fixed calendar, adjusting for rainfall received and mulch effectiveness.

What do you think? With labour shortages rising in rural India, could wider adoption of drip irrigation combined with polythene mulching replace manual weeding in mulberry gardens-or would the cost and environmental concerns outweigh the benefits for small-scale sericultural farmers?

References

1. https://www.fao.org/4/x9895e/x9895e04.htm
2. https://www.agricolbikaner.org/wp-content/uploads/2020/10/L-13.pdf
3. https://www.apnikheti.com/en/pn/agriculture/horticulture/fruit/mulberry
4. https://silks.csb.gov.in/ramanagara/mulberry-crop-production-technology/
5. https://www.sciencedirect.com/science/article/pii/S221078431630290X
6. https://www.researchgate.net/publication/334480941_Impact_of_Black_Polythene_Mulching_in_Mulberry_Garden_on_Weed_Infestation_Soil_Moisture_Plant_Growth_and_Leaf_Yield_under_Tropical_Conditions
7. https://www.frontiersin.org/journals/agronomy/articles/10.3389/fagro.2024.1361697/full
8. https://arccjournals.com/journal/agricultural-reviews/R-2350