Saline Water & Blend It Without Losing Yield

Often yes. Because electrical conductivity mixes roughly linearly by volume, blending a salty source with fresh water gives an applied salinity of ECblend = f·ECsaline + (1−f)·ECfresh, where f is the saline fraction. As long as the resulting root-zone ECe (about 1.5 × the applied ECw at a 15–20% leaching fraction) stays at or below your crop's salt-tolerance threshold, you keep full yield. The calculator finds the blend EC and the largest safe saline share for your crop.

The blend EC is the volume-weighted average of the two sources: ECblend = f·ECsaline + (1−f)·ECfresh. For example, a 50:50 mix of 0.6 dS/m fresh and 6.0 dS/m saline water gives 0.5·6.0 + 0.5·0.6 = 3.3 dS/m. That applied ECw then raises the average root-zone ECe to about 1.5 × ECw, which the tool compares with the crop threshold.

It is the largest share of saline water in the mix whose blended EC keeps the crop at your chosen target yield. The tool solves f = (ECw_limit − ECfresh) / (ECsaline − ECfresh), where ECw_limit is the applied EC that holds the crop at the target. If even pure fresh water exceeds the limit the safe fraction is 0; if your saline source is already within tolerance it can reach 100%.

Blending mixes the two waters and applies the same salinity at every irrigation. Cyclic use keeps the waters separate: you irrigate the salt-sensitive germination and seedling stages with fresh water and switch to saline once the crop is established and more tolerant. The season-average salinity can be the same, but cyclic use protects the vulnerable early stages, so it often loses less yield than a constant blend at the same overall saline share.

Salts concentrate in the root zone as the crop transpires water and leaves salts behind. At a typical 15–20% leaching fraction, FAO Irrigation & Drainage Paper 29 uses ECe ≈ 1.5 × ECw for the average root-zone salinity. Higher leaching lowers the factor; very little leaching raises it. The tool uses the 1.5 factor and reports the implied root-zone ECe.

The leaching requirement (LR) is the fraction of applied water that must drain past the root zone to stop salts accumulating. FAO-29 gives LR = ECw / (5·ECe − ECw), where ECe is the salinity the crop can tolerate for the target yield. Saltier water needs more leaching; the tool reports the LR so you can size the extra water — for example, an LR of 0.10 means applying about 10% more water than the crop uses.

Salt-tolerant field crops such as barley (threshold 8.0 dS/m ECe), cotton (7.7), sugar beet (7.0) and bermuda grass (6.9) can use quite saline water, while sensitive crops such as beans, carrots, onions, strawberries and most fruit trees (thresholds around 1.0–1.7 dS/m) lose yield quickly. The tool ranks each crop by its Maas–Hoffman threshold and slope so you can match the source to the crop.

Wheat holds full yield up to a soil ECe of about 6.0 dS/m and loses ~7.1% per dS/m above that. Applied water of 3 dS/m gives a root-zone ECe near 4.5 dS/m, still under the threshold, so wheat keeps essentially full yield. The same water on a sensitive crop like beans (threshold 1.0 dS/m) would cause a heavy loss — the calculator shows the difference per crop.

It assumes relative yield stays at 100% until soil salinity (ECe) passes a crop-specific threshold, then declines linearly at a fixed slope (percent per dS/m) to zero. Threshold and slope are field-trial means tabulated in FAO-29 Rev.1 (Ayers & Westcot 1985) from Maas & Hoffman (1977). Real results vary with climate, variety, irrigation method and the salt composition of the water.

Yes. Drip keeps the wetted zone continuously moist and pushes salts to the wetting front, so crops often tolerate slightly saltier water under drip than under furrow or sprinkler. Sprinkler can also cause leaf burn from salt deposited on foliage. The tool works on root-zone ECe; for sprinkler on sensitive foliage, treat the result as optimistic and consider night irrigation.

The tool computes it directly: it converts the blend EC to root-zone ECe, applies the crop's threshold and slope, and reports relative yield and the percent loss. For instance, tomato (threshold 2.5 dS/m, slope 9.9% per dS/m) irrigated with a blend giving ECe 7.4 dS/m retains only about 50% yield, while barley at the same salinity stays at 100%.

It can, if you do not leach. Even a 'safe' blend adds salt every irrigation; without a leaching fraction those salts concentrate and root-zone ECe creeps up season after season. That is why the calculator pairs the safe blend with a leaching requirement — apply that extra fraction of water (and ensure drainage) to keep the salt balance steady.

If fresh water is scarce, blending or cyclic use stretches it across more area or more of the season while keeping yield acceptable — that is the whole point. If you have enough fresh water for the sensitive stages, a cyclic strategy (fresh early, saline later) usually beats a constant blend for the same total saline use. Use the blend-vs-cyclic comparison to decide.