Effective Irrigation and Soil Moisture Conservation Techniques for Mulberry Cultivation

Mulberry is the sole food source for the silkworm (Bombyx mori), making it a backbone crop of the sericulture industry. The quantity and quality of mulberry leaves directly depend on how well the plants are watered and how effectively the soil retains moisture. In India alone, mulberry covers over 282,000 hectares across various agro-climatic zones-from the tropical plains of Karnataka to the sub-tropical belts of West Bengal. Whether a farmer relies on canal water, tube wells, or monsoon rain, choosing the right irrigation method and moisture conservation strategy can mean the difference between 15 tonnes and 45 tonnes of leaf yield per hectare per year.

Why irrigation matters in mulberry cultivation 🔗

Mulberry is a fast-growing, deep-rooted perennial that demands a consistent supply of water throughout its growth cycle. Irrigated mulberry produces leaves with higher moisture content, more protein, and better nutritive value compared to rain-fed crops. Research shows that leaf production can increase three to four times when balanced fertilizers are combined with proper irrigation. On average, mulberry needs about 340 cubic metres of water per hectare every ten days in loamy soils, with that interval extending to about 15 days in heavier clay soils. During the active sprouting and leaf development stages, more frequent irrigation is essential. In tropical India, where mulberry grows year-round, 12 to 15 supplemental irrigations may be needed between November and April alone to compensate for low rainfall.

Water quality also plays a role. Irrigation water for mulberry should ideally contain less than 1,000 parts per million of total soluble salts. Poor-quality water can lead to salt build-up in the soil, stunting plant growth and reducing leaf quality over time.

Common irrigation methods for mulberry 🔗

Several irrigation techniques are practised in mulberry gardens, each suited to different field conditions, water availability, and budgets. Let’s look at the main options.

Furrow irrigation 🔗

Furrow irrigation is one of the most widely used surface methods. The field is laid out into a series of ridges and furrows, and water is channelled through the furrows, seeping laterally and downward into the root zone. This method works well on gently sloping land and is one of the oldest and most straightforward approaches to crop irrigation. It is relatively inexpensive to set up and suits clayey or loamy soils where water spreads well across the bed. However, furrow irrigation can lead to uneven water distribution if the land is not properly graded, and water losses through runoff and deep percolation can be significant on sandy soils.

Flat bed and basin irrigation 🔗

In the flat bed method, the field is divided into rectangular beds with raised bunds on all sides and supply channels along the edges. Water floods each bed uniformly. This method is suitable for all soil types and is commonly used in smaller mulberry plantations. Basin irrigation is a closely related technique, particularly adopted for tree-form mulberry plantations. Small basins are created around each plant trunk, and water from the supply source flows directly into these basins. The advantage is minimal evaporation loss and no soil erosion, though it can be labour-intensive.

Sprinkler (overhead) irrigation 🔗

Sprinkler systems distribute water through a network of pipes and nozzle heads, spraying it over the field. This method is useful on undulating or uneven land where surface irrigation is impractical. According to the University of Missouri Extension, sprinkler systems allow precise control over the amount of water applied and can deliver very small quantities per application. In mulberry cultivation, sprinklers also help distribute water uniformly across foliage. The downsides include water loss through evaporation and wind drift, higher energy costs for maintaining pressure, and the possibility of clogging when water quality is poor.

Drip irrigation 🔗

Drip irrigation is considered the most water-efficient method for mulberry cultivation. Water is supplied under low pressure through plastic tubing fitted with emitters, delivering it drop by drop directly to the root zone. This eliminates losses from surface runoff and significantly reduces evaporation. A study published in the Archives of Agronomy and Soil Science found that low-cost drip fertigation in mulberry reduced water requirement by 24%, while water-use efficiency increased by 61% and nitrogen-use efficiency by 63% compared to conventional surface irrigation. The paired-row planting system (90+150 cm × 60 cm spacing), now widely recommended in Indian sericulture, is specifically designed to accommodate drip lines between rows, making the system even more practical. The main limitation is a higher initial installation cost, and emitters can clog if water contains high levels of iron or sediment.

Choosing the right irrigation method 🔗

The best irrigation method depends on several practical factors: the type of soil in the garden, the slope and shape of the field, the availability and quality of water, and the farmer’s budget. For small rain-fed gardens, basin irrigation is a practical and low-cost choice. For large commercial plantations with reliable water access, drip irrigation offers the highest returns over time despite the upfront expense. Sprinkler systems fill the gap for farmers working with uneven terrain or sandy soils where surface methods lose too much water. Many state sericulture departments and the Central Silk Board offer subsidies for micro-irrigation systems, making the switch to drip more affordable for small and marginal farmers.

Soil moisture conservation: making every drop count 🔗

In rain-fed areas-which contribute a major share of India’s silk production-irrigation infrastructure may be limited or absent. Here, soil moisture conservation becomes critical. The goal is to minimise water loss from evaporation and runoff, and to maximise the amount of rainwater that soaks into the root zone. The Climate Technology Centre & Network (CTCN) describes soil moisture conservation as primarily relying on low-cost, locally available methods that provide cover for the soil and reduce evapotranspiration. Let’s explore the key practices relevant to mulberry.

Fall ploughing (deep summer ploughing) 🔗

Fall ploughing, also called deep summer ploughing, involves turning the soil to a depth of 30-35 cm during the dry season, well before the onset of monsoon rains. This breaks up compacted soil layers and increases the soil’s porosity, allowing rainwater to infiltrate deeper rather than running off the surface. It also exposes dormant weed seeds and soil-borne pests to sunlight and heat, reducing their population. For mulberry, the FAO recommends that land be ploughed deep with a heavy mould board plough, followed by repeated ploughing to bring the soil to a fine tilth before planting. This practice is especially beneficial in heavy clay soils that tend to form a hard crust during the dry season.

Compartmental bunding 🔗

Compartmental bunding involves creating small earthen embankments (bunds) around sections of the field to divide it into compartments. Each compartment traps rainwater within its boundaries, preventing it from flowing away as runoff. This technique is particularly effective on sloping land and in areas with erratic rainfall. In hilly regions, constructing terraced or contour bunds helps slow down water movement across the slope, giving it more time to infiltrate the soil. The bunds can be combined with flat bed or basin irrigation layouts to serve dual purposes-capturing rain and channelling irrigation water efficiently.

Mulching 🔗

Mulching is one of the most effective single strategies for conserving soil moisture. It involves spreading a layer of organic or inorganic material over the soil surface around the mulberry plants. Common organic mulches include dried leaves, rice straw, grass clippings, and wood chips. This layer acts as a shield-reducing evaporation by blocking direct sunlight and wind from the soil surface, moderating temperature fluctuations, and suppressing weed growth. Research published in Agronomy notes that organic mulching minimises soil deterioration, enhances organic matter content, and improves the soil’s water-holding capacity. A study on black polythene mulching in mulberry gardens from the Central Silk Board found that this practice increased soil moisture content by over 50% and boosted mulberry leaf yield by about 58% compared to fields with no mulch. As organic mulches decompose over time, they also add nutrients back into the soil, creating a beneficial cycle of moisture conservation and soil enrichment.

Green manuring 🔗

Green manuring involves growing specific crops-typically fast-growing legumes like dhaincha (Sesbania), sunhemp, or cowpea-between mulberry rows and then incorporating them into the soil before they flower. When ploughed into the earth, this plant biomass decomposes and adds organic matter, which significantly improves the soil’s ability to hold water. Leguminous green manure crops also fix atmospheric nitrogen through their root nodules, reducing the need for chemical fertilizers. According to ATTRA (National Center for Appropriate Technology), about 50% of the nitrogen contained in a green manure crop becomes available to the following crop after incorporation. The ideal window for green manuring in mulberry is during the monsoon season, when the crop’s own growth rate naturally slows. The green manure crop should be allowed to grow for 45-60 days before being cut and worked into the soil, ensuring maximum biomass without competing with mulberry during its active growth periods.

Contour ploughing and conservation tillage 🔗

On sloping land, ploughing along the contour rather than up and down the slope creates natural barriers that slow runoff velocity and allow water to soak into the soil more evenly. This simple change in ploughing direction can dramatically reduce both water loss and soil erosion. Conservation tillage-where crop residues are left on the soil surface instead of being removed or burnt-adds another layer of protection. The residues reduce the impact of raindrops on bare soil, lower evapotranspiration, and slowly decompose to improve soil organic content.

Integrating irrigation with moisture conservation 🔗

The best results come from combining efficient irrigation methods with soil moisture conservation practices rather than relying on either alone. A farmer using drip irrigation, for instance, can further reduce water consumption by applying organic mulch around the base of each plant. Compartmental bunding can capture and store monsoon rainfall during the wet season, reducing the number of irrigations needed in the dry months. Green manure crops grown during the monsoon enrich soil organic matter, which improves water retention for the entire year ahead.

Monitoring soil moisture regularly is another practical step. Simple tools like tensiometers or gravimetric sampling can help farmers determine when irrigation is truly needed, preventing both under-watering and over-watering. The irrigation frequency should be adjusted based on the growth phase of the mulberry plant, the soil type, and local weather conditions. During the sprouting and rapid leaf development stages, more frequent watering is needed, while established plants with deep root systems can tolerate slightly longer intervals.

Adequate drainage is equally important. Waterlogged conditions starve mulberry roots of oxygen, causing wilting and poor root respiration. Ensuring proper drainage channels and avoiding over-irrigation are just as critical as providing enough water.

Practical tips for mulberry farmers 🔗

Match the method to your conditions: Use drip irrigation where water is scarce and subsidies are available; opt for furrow or basin methods in flat, clay-rich fields with plentiful water.

Mulch consistently: Apply a 7-10 cm layer of organic mulch from the plant base to the canopy drip line. Replenish as it decomposes.

Time your green manuring: Sow leguminous green manure crops at the start of the monsoon and incorporate them within 45-60 days, well before the next harvest cycle begins.

Plough deep before the rains: Summer ploughing opens up compacted soil layers and improves rainwater infiltration for the entire monsoon season.

Build and maintain bunds: Repair compartmental bunds before each rainy season to ensure they effectively capture and hold water.

Monitor and adjust: Check soil moisture levels before irrigating. On clay loam soils, irrigating once every 15 days may suffice; sandy soils may need water every 8-10 days.

What do you think? How can small and marginal sericulture farmers in rain-fed regions best combine these irrigation and moisture conservation strategies to maintain consistent leaf yields throughout the year? And could solar-powered drip systems become a practical solution for areas where both electricity and water are scarce?

References

1. https://www.fao.org/4/x9895e/x9895e04.htm
2. https://www.usgs.gov/water-science-school/science/irrigation-methods-furrow-or-flood-irrigation
3. https://extension.missouri.edu/programs/irrigation/irrigation-system-pros-and-cons
4. https://www.tandfonline.com/doi/abs/10.1080/03650340.2020.1852552
5. https://siddipet.telangana.gov.in/horticulture-sericulture/
6. https://www.ctc-n.org/technologies/soil-moisture-conservation-techniques
7. https://www.mdpi.com/2073-4395/12/8/1881
8. 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
9. https://attra.ncat.org/publication/overview-of-cover-crops-and-green-manures-2/