0.4
40
%
6,000
kg/ha
60
%
0.667
0.4
40
%
6,000
kg/ha
60
%
0.667
The Harvest Index (HI) Calculator computes the ratio of economic yield (the harvested product such as grain, tubers, or fruit) to total above-ground biological yield. Harvest Index is a measure of how efficiently a crop converts total biomass into the harvestable product and has been a key target of plant breeding programs. Modern crop varieties typically have higher HI than older cultivars due to improved partitioning of resources to grain.
Enter the economic yield and total biological yield (both in kg/ha or any consistent unit) to obtain the Harvest Index as both a decimal and a percentage, plus the residue yield.
The calculator uses the standard Harvest Index definition:
Economic yield is the grain, tuber, fruit, or other marketable product. Biological yield is the total above-ground dry matter, including both the economic product and vegetative parts (straw, stalks, leaves). Both must be measured on the same moisture basis, preferably dry weight.
Inputs
Results
Modern wheat with 4,000 kg/ha grain from 10,000 kg/ha total biomass has an HI of 0.40 (40%), typical of improved varieties.
Inputs
Results
A high-yielding rice crop with 5,500 kg grain per 12,000 kg biomass achieves an HI of 0.46 (46%).
Typical HI values vary by crop: modern wheat and rice varieties achieve 0.40-0.55, maize 0.45-0.55, soybean 0.35-0.50, and potato (tuber:total) 0.70-0.85. Traditional varieties often had HI below 0.30. The "Green Revolution" dramatically increased HI through breeding for shorter stems and larger grains, which was the primary driver of yield increases.
Historical yield gains in cereal crops came largely from increasing HI rather than total biomass. Semi-dwarf wheat and rice varieties introduced in the 1960s-70s redirected resources from straw to grain, dramatically increasing yields. However, HI has biological limits (theoretical maximum around 0.60 for cereals), so future yield gains may need to focus on increasing total biomass as well.
Yes. Drought, heat, nutrient deficiency, and disease stress during reproductive growth stages can dramatically reduce HI because they impair grain filling while the plant has already invested in vegetative growth. This is why late-season stress often causes proportionally greater yield loss than early-season stress, as the plant cannot redirect accumulated biomass back to grain.
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