Soils for Farmers




Common Farm Soil Problems

Common soil problems on farms in California

Common soil problems on farms in California:

1) Nitrogen and Phosphorus deficiencies, 2) Low Soil Organic Matter and poor soil tilth (where “tilth is the fitness as a medium for growing plants & other organisms.”), 3) Soil Salinity, and 4) Nematodes and soil-borne diseases.

Is it my soil


Click to see what’s likely causing the problem with your plants?

Determine your soil type at Soil web (T O’Geen) - a remarkable map resource showing soil types throughout California with detailed information on soil characteristics and potential uses.


Opportunities to Improve Farm Soils

Opportunities to Improve Farm Soils

Learn more below about options, but in summary, the primary options to address major challenge are:

1) Nutrient deficiencies: Add fertilizer through either organic or inorganic sources, 2) Soil salinity: Control or amend through water management practices, 3) Soil tilth: Add plant material (cover crops, mulching, compost) or preserve (e.g., reduced tillage) soil organic matter levels to create conditions favorable for microbial activity. 4) Nematodes and diseases: Use Integrated Pest Management for field evaluation and management options.

Practices to build Healthy Soils


Practices to build Healthy Soils


Animal Management and Cover Crops 

animals and cover crops

Pros, Cons and Considerations.

Animals can save costs of cover crop incorporation, but they can lead to increased compaction. Animals require constant management and in some areas predators can be problematic. Soil compaction has been noted in some fields following animal grazing. 


See more on cover crops below

When can I put my animals in with my cover crop?

What cover crops are appropriate for animals to graze?

See SAREP Cover Crop DBase for the individual crops for grazing suitability

What are the food safety considerations? Fact sheet (Suslow and Harris)



(Lead Margaret Lloyd)

compost for farmers

Pros, Cons and Considerations.

Soil Organic Matter

Compost and mulch can build Soil Organic Matter levels which can

  • improve soil water holding capacity 
  • improve soil structure, aeration and water infiltration
  • increase N and other nutrient availability 
  • Sequester C (i.e., grab carbon from th air)
  • (decrease crusting?)

While building Soil Organic Matter is highly desirable - It is easily said, but much harder to do. 

Water & Erosion

Surface mulch or compost can

  • reduce evaporation losses
  • protect the soil surface and so reduce surface crusting and help increase water infiltration and reduce run off (and erosion)

Where do I find a certified producer of compost/much?

See STA certified producers in California

Mulch? Compost? Fertilizer?

What's in the different products? Fact sheet 

Note. Composts and manures typically have 1-4% N

Assessing compost quality for Agriculture Fact Sheet

Making compost on the farm Video (Vossen)

How much should I add?

Annual crops and Orchard crops:

Coming soon (To reduce evaporation - you need around 5 “ of surface mulch; To reduce weeds, you need enough so the weed seeds can’t see the sun. To add as a nitrogen source: Amount compost/mulch required to provide the equivalent N needed = Target N rate *100 / Percent N in compound. However, only about 5% of this will be available for the first season. (coming as an on-line tool)


Composting Almonds Web (Almond Doctor)

Mulching Almonds Web (Almond Doctor)

How do I spread and incorporate?

Should I be worried about heavy metal accumulation? SAREP 

How do I mitigate for or calculate salt accumulation?

What are the food safety considerations? Fact sheet (Suslow and Harris)


Also see Compost (web UC Davis)


Cover Crops

(Lead Sarah Light)

soil cover crop

Pros, Cons and Considerations.

Adds plant matter through cover crops to build Soil Organic Matter which can potentially

  • improve soil water holding capacity
  • improve soil structure
  • increase N and other nutrient availability 
  • Sequester C (i.e., grab carbon from th air)

Cover crops can also provide soil cover and bind the soil to reduce erosion. 

Cover crops come with costs - seed costs, time, labor, water, tillage.

Time can be important in two ways - the actual time required to manage the cover crop and then the time the cover crop needs in the field. This growing season for the cover crop has to be managed around other operations - e.g., when does the field need to be ready for planting the following crop. This may limit the time suitable for cover crop growth and so limit cover crop benefit. 


About cover crops Fact sheet (Ingles)

Cover crops in Organic systems Manual (SARE)

What cover crops are best where?

Cover crops by zone in California (USDA)

Summary options (SAREP)

DBase of options (SAREP)

How should I manage my cover crops?

Annual crops Manual

Orchard crops

Seed selection web

Almonds Cover crops in Biologically managed Organic Almond Systems BIOS Manual

Cover crops in Orchards Manual

Cover crops in Walnuts Manual ; Manual BIOS

Cover crops in Vineyards Manual


How do I manage animals and cover crops?

How much N is in my cover crop?

Plant Available N and Cover crops Manual (SARE) ; Plant Available N and Cover crops Fact Sheet (Lloyd)

Content for some common cover crops Table (SAREP)


Fertilizer and Soil pH (organic and inorganic)

(Lead Daniel Geisseler)


Pros, Cons and Considerations.

Inorganic and organic sources of nutrients can overcome soil deficiencies and enhance plant growth. There is of course the debate between inorganic and organic sources. One advantage of many organic sources is the inclusion of carbon which can help build soil organic matter. An advantage of inorganic can be the higher content of certain nutrients (e.g., nitrogen) meaning less product has to be handled and spread.

pH - Nutrient availability and microbe activity vary with pH - See Figure (from Fairway Green Inc)


Nutrient needs (Timing and Form)

California fertilization guides (Geisseler)

Nutrients from Organic Sources Fact Sheet

What nutrients are in the different products? Fact sheet 

Converting lb/ac to

Converting lbs/small areas Fact sheet ; Calculator

Estimating lbs/foot row Fact sheet (U Fl)


Decision Support Tool: CropManage Sign in required (Cahn)


Soil pH

What's the effect of fertilizer on soil pH? Fact Sheet

  1. Why and how Change soil pH Fact Sheet (Vossen)
  2. What’s the difference between lime and gypsum Fact sheet

Also see: Acidity (web UC Davis) & "What is pH and Why do we care" Fact sheet

What are the reporting requirements for on-farm Nitrogen use? 

Irrigated lands Regulatory Program Web (California Water Boards)



Integrated Pest Management

(Lead Jim Farrar)


Pros, Cons and Considerations.

IPM is now the preferred standard for dealing with soil borne (and other) pests and diseases.

Soil borne diseases in vegetables Fact Sheet

UC IPM Integrated Pest Management

Explore UC Integrated Pest Management


Riparian areas

Tillage (Conservation Tillage and Deep Tillage)


conservation tillage

Pros, Cons and Considerations.

Conservation tillage

Reduced tillage is widely recognized as a way to lower tillage costs and build up soil organic matter. 

Reduced tillage systems require specialized equipment to handle residues and to plant in to undisturbed or minimally disturbed soils. 

Conservation Tillage and Weed Management Fact sheet


Deep tillage

Deep tillage (sometimes called deep ripping) can be used to break compaction layers in the soil profile - thus allowing roots to explore the soil to greater depth accessing more water and nutrients.


What tillage system is economic for my soil?

Benefits of residues in Conservation Ag Video (CASI)


How do I break a compaction layer?

Deep tillage (or ripping) is often recommended to break hardpans and to increase water infiltration.

For deep ripping to be effective:

  • The ripping tines must be able to penetrate just below the compacted soil layer
  • Soil must be moist enough to allow penetration of the ripping tines but not so moist that the tines cause smearing without fracturing and shattering the soil.

(for more DPI West. Aust)


Managing Salinity 


Pros, Cons and Considerations.

Nearly all water contains salts. As water evaporates from the soil, salts in applied water can accumulate in the root zone. Irrigation and rainfall can move those accumulated salts out of the root zone.

Salinity can also occur when the water table is near the surface. Water is drawn to the soil surface (by a process called capillary rise), the water evaporates, leaving the salt.


Managing Salinity.

What water can I use, how much, how apply and when?

About Salinity Management

Salinity Management Practices

Also see Salinity (web UC Davis)


Water Management


water in hands

Pros, Cons and Considerations.

Irrigation method can greatly influence water efficiency.



What about water quality?

Irrigation water quality 

Water Requirements 

Decision Support Tool: Log in required - CropManage (Cahn)

Irrigation methods and management

Irrigation management (Schwankl)

How to manage crops when water is limited?

UC Drought (Schwankl)

Drought & water management information

Irrigation Management of Winegrapes with a Limited Water Supply (Schwankl)


Vineyard irrigation Sonoma (Rhonda Smith)

Nitrogen monitoring requirements

Visit Irrigated lands Regulatory Program Web (California Water Boards)


Also see Excessive water and Poor Drainage (web UC Davis)


More Resources on Soils and Farming