YieldAI field guide · Soil & fertility

Cover Crops for Soil Health: What to Plant & Why

Updated 2026-07-102 min read4 practical chapters

Why this matters

A cover crop is grown to feed and protect the soil rather than to sell. Done well it is the cheapest way to build organic matter, fix free nitrogen, break pest cycles, smother weeds and stop erosion — turning your off-season from a liability into an investment in next year’s yield.

Chapter 01

What cover crops do for you

Build organic matter & feed soil life — living roots keep microbes and mycorrhizae fed year-round.
Fix nitrogen — legumes can add meaningful N for the following crop.
Stop erosion & hold nutrients — cover keeps soil and nitrates from washing away over winter/monsoon.
Smother weeds and break pest/disease cycles between related cash crops.
Relieve compaction — deep taproots (radish) open the subsoil.

Chapter 02

Choose by the job you need done

Pick the family that matches your goal:

Legumes (sunn hemp, cowpea, clover, vetch, dhaincha) — fix nitrogen; best before a hungry crop like maize or a vegetable.
Grasses/cereals (rye, oats, sorghum-sudan, millet) — lots of biomass, scavenge nitrogen, smother weeds, great erosion cover.
Brassicas (mustard, tillage radish) — bust compaction and biofumigate against some soil pests.
Mixes — combine a legume + grass + brassica to get several benefits at once and more resilient cover.

Chapter 03

Fit it into your rotation

Use whatever window you have: a winter cover after a summer crop, a summer green manure before a winter crop, or a fast catch crop in a short gap. Sow densely into a firm, moist seedbed for quick ground cover. In hot regions a 45–60 day sunn hemp or dhaincha green manure before the main crop is a classic, cheap fertility builder.

Chapter 04

Terminate at the right time

The biggest mistake is letting a cover crop go to seed (it becomes next year’s weed) or robbing the cash crop of moisture. Terminate at or just before flowering, when biomass and nitrogen peak:

Incorporate as green manure 2–3 weeks before planting, or
Roll/crimp or mow and plant into the residue for no-till moisture conservation.

Leave a short gap before sowing the cash crop so decomposition does not tie up nitrogen at emergence.

MAKE IT SPECIFIC TO YOUR FARM

Turn this guide into a field-ready answer.

Ask YieldAI about your crop, location, soil or current field condition—in your language.

Ask YieldAI free →

Frequently asked questions

Which cover crop fixes the most nitrogen?

Legume cover crops such as sunn hemp, cowpea, dhaincha, clover and vetch fix nitrogen through their root nodules and can supply a meaningful share of the next crop’s needs, especially when terminated at flowering when nitrogen peaks.

When should I terminate a cover crop?

Terminate at or just before flowering, when biomass and nitrogen are highest and before it sets seed. Incorporate it 2–3 weeks before planting, or roll/mow it and plant into the residue for no-till.

Can cover crops break up compacted soil?

Yes — deep-rooted brassicas like tillage radish and forage crops drill channels through compacted layers, and their decaying roots leave pores that improve water infiltration and rooting for the next crop.