Providing adequate nutrients to plants in Nevada’s poor soils is a challenge! Less than 1 percent organic matter to hold on to nutrients and release them slowly. Tonight, I’m going to teach you some strategies for providing needed nutrient to your garden while improving the overall health of your soil.
These are taken up as gases through those small pores on the leaf surfaces.
Some nutrients are needed in larger amounts than others.
Phosphorus has many functions in plants, including development of flowers, fruits, and roots. However, there is no evidence that providing extra P will encourage production of flowers, fruits and roots. The balance between N and P is most important.
Potassium also has many essential functions in plants, including sugar formation and movement in plants, formation of chlorophyll, and leaf stomate opening and closing for gas exchange with the air. Like nitrogen, potassium is very prone to leaching in soils. And plants will tend to take up as much as you want to give them – even if they don’t need it, so it’s easy to waste money on excess fertilizer. Also, over-fertilizing with potassium (and nitrogen for that matter) will injure plants by killing the root and leaf tips.
This is a fundamentally different form of production in which the focus is more on soil-building and working with the living organisms that are naturally present.
This is a picture of the soil food web – showing how a good soil can take N2 from the air and convert it to nitrogen fertilizer by way of beneficial soil microbes. It takes time to get your soil to this level of productivity but you can contribute by adding organic matter every year (especially manure, compost, and cover crops).
This approach to fertility management in organic production relies on natural cycles and carefully planned human practices to replenish the soil with nutrients extracted during a production cycle. Organic matter is incorporated into the soil to be decomposed by soil microbes to release nutrients by the process of mineralization.
Some people try to emulate synthetic fertilization practices by picking and choosing the timing of application of specific organic products. However, this is not necessary if you use an organic product that comes from a combination of sources. In fact, composts and manures are less expensive and a good way to provide a balance of nutrients for your soil. Because the nutrients are slowly released, your plants will take up what they need when they need it.
Cover crops (also sometimes called green manures) are plants grown, not for harvest, butfor the express purpose of incorporating them back into the soil to increase organic matter levels.Cover crops can, in addition to improving soil physical conditions, aid in the control of erosionand weeds, and prevent compaction. They also provide a habitat for beneficial insects, improvesoil fertility, stimulate soil biological activity, and absorb and help recycle plant nutrients,especially nitrogen, between growing seasons.
Heavy feeders include cabbage, cauliflower, all leaf vegetables such as lettuce, spinach and celery. Also included are leeks, cucumbers, squash, sweet corn and tomatoes.
Hairy vetch is widely used by organic growers in the United States as a winter cover crop, as it is both winter hardy and can fix as much as 200 lb/acre of atmospheric nitrogen. Disadvantages of hairy vetch in production agriculture are related to the crop having a portion of hard seed and its tendency to shatter seed early in the season - leading to it remaining in the field as a weed later in the season. This can be a particular problem in wheat production.Companion plantOrganic gardeners often plant hairy vetch (a nitrogen-fixing legume) as a companion plant to tomatoes, as an alternative to rotating crops in small growing areas. When it is time to plant tomatoes in the spring, the hairy vetch is cut to the ground and the tomato seedlings are planted in holes dug through the matted residue and stubble. The vetch vegetation provides both nitrogen and an instant mulch that preserves moisture and keeps weeds from sprouting.
Not to be confused with Austrian peaweed or Swainsonpea – a common contaminant of alfalfa fields
You may have to transition to organic production because building healthy soil takes time. You can monitor the progress of your program by getting your soil tested annually for nutrients (list of soil testing labs on grow your own website). Use the same lab each year and keep a file of your reports so you can monitor your progress over time.
Shallow rooted: broccoli, corn, lettuce, potatoes, cabbage,spinachAnother strategy to manage soil fertility is to make sure you’re using nutrients present at different depths in your soil horizon by planting crops with different rooting depths near one another.
Grow Your Own, Nevada! Spring 2013: Nutrients & Fertilizers for your Vegetables
Heidi Kratsch, State HorticultureSpecialist
Mineral elements involved in themetabolism of the plant ornecessary for it to complete its lifecycleExample: K+NO3-
CarbonOxygenHydrogenAvailable from the air or water(Carbon from CO2 made available by photosynthesis)
Often the most limiting nutrient for plantgrowth Proteins and chlorophyll Necessary for photosynthesis
Reduced growth,smaller leaves Chlorosis (yellowing)greater in olderleaves Common in sandysoils low in organicmatter Over-irrigation Easily leached fromthe root zone.
Deficiency seen aspurpling of leafveins. Important in rootand seeddevelopment. More efficient in thepresence of nitrogen. Rarely deficient inwestern soils, exceptwhen soils are cold.P-deficiency in pepper plantedtoo early in the season
Movement ofsugars in plants Increases size andquality of fruitsand vegetables Leaches readily Deficiency causesmarginal leafchlorosis of olderleaves Potassium deficiency in soybean
Liquid Mostly quick-release Last 3 to 4 weeks Most areconcentrates – mixwith water Apply with hose-end sprayer or awatering can
Granular Apply dry and water in Quick-release, ex.Ammonium sulfateSlow-release Sulfur-coated, lasts forabout 8 weeks. Polymer-coated, lasts forabout 12 weeks.
Synthetic Organic Provide a quicklyreleased source ofnutrients ondemand Can cause leaching Fertilizer burn Timing isimportant! Goal is to enhancesoil for beneficialmicrobes that candecompose organicmatter. Slowly released Lower nutrientvalues Look for certifiedorganic products.
Leafy Root + Fruit-bearing Use a balancedfertilizer early in theseason. 10-10-10 16-16-16 Use a low N completefertilizer early in theseason: 6-24-24 6-12-18 8-16-16Heavy feeders require a SECOND fertilization with N during the season:Corn, garlic, onions, potatoesFIRST:Avoid N fertilization of fruit-bearing crops too close to flowering.
Apply fertilizer 3 to6 inches to one sideof plant or row. Water it in. Keep dry fertilizeroff the leaves.
“an ecological production managementsystem that promotes and enhancesbiodiversity, biological cycles and soilbiological activity”
Organic sources of N Organic sources of P Bat guano Blood meal Cottonseed meal Fish emulsion Fish meal Bone meal Rock phosphates Kelp meal SeaweedOrganic sources of KComposts and manures are good naturalfertilizers for Nevada soils.
Usually planted in the “down” season(such as winter) – not harvested forconsumption Used for soil enhancement (called“Green Manure”)
Increase soil organicmatter Increase nitrogenbalance in the soil Suppress pests(weeds) Provide habitat forbeneficial insects Enhance soilbiological activity Control erosion Prevent compactionWhat do you want your cover crop to do?
Legumes:◦ Alfalfa◦ Beans – all kinds◦ Clover◦ Lentil◦ Peas Interplanted withheavy feeders:◦ Cabbage◦ Cauliflower◦ Celery◦ Corn◦ Cucumbers◦ Leeks◦ Lettuce◦ Spinach◦ Squash◦ TomatoesInterplanted rows of corn with clover
In rotation: 2- or 3-year Winter cover crop Summer cover crop Strip cropping IntercroppingCowpea as a summer cover toincrease soil nitrogen levelsand suppress weeds
Mowed cereal ryeas a mulch tosuppress weeds. Use with vegetablesthat have largeseeds or aretransplants. Cut at flowering butbefore seed set.
Drought tolerant Excellent mineralizedN provider Grows slowly in fallbut resumes in spring Smothers springweeds Enhances soil moistureretention Sprawling vines can bea challengeWinter annualZone 3 - 6Great in an area where tomatoes or corn will be grown!
Early September Seeding rate of 1-2 lb./1000 ft2 Requires inoculationwith Rhizobium Comes as dry powdermixed with finelyground peat moss
Winter annual thatmay die in winter incolder parts ofNevada But, establishesquickly If winter-killed, noneed to pull up… Can combine withwinter ryeSeed Austrian pea at 2-4 lb./1000 ft2Winter annualZone 6
Greater control ofwinter annual weeds More organic matterresidue Provides proper C:Nratio to speeddecomposition in soil Use 40-60% grain fullrate and 80% legumefull rateHairy vetch with winter rye
Hardiest of cover crops Rapid establishment Deep fibrous rooting Builds organic matter Breaks up compaction Allelopathy suppressesweed seeds Often grown with alegumeWinter annualZone 4Seed at 2.5 lb/1000 ft2
Fall-seeded brassica Forms thick, white taproots 8-14 inches long! Nicknamed “biodrill” or“tillage radish” Seed in late August, willwinter-kill in much ofNevada Traps soil nutrients,breaks up compaction,biofumigant properties(against nematodes)
The best time to planta cover crop is anytimea bed is not covered byfood crop or mulch. Make a furrow for largeseeds Scatter and rake insmaller seeds Tamp the bed toensure good soilcontact and water in.Nature abhors a vacuum. Bare groundinvites weeds and represents a lostopportunity to improve the soil.
Choose cropsappropriate for ourarea. Irrigate onlyenough to avoidplant stress. Use drip irrigationto avoid waterwaste. Irrigate less inwinter. While buckwheat is a fast-growingsummer annual cover crop, itrequires more water than is efficientfor our region.
Tilling – avoid deepmechanical tillage Mowing Remove plants and useas compost or mulch Pen chickens in the field(except hairy vetch –seed is poisonous tochickens) Incorporate cover crop 3weeks before food cropis plantedTurning in a cover crop by hand is atedious job. Top mowing or use of agarden tiller can facilitate the process.
Chickens can remove a cover crop in 2 weeks. BUT don’t letchickens graze in hairy vetch that has done to seed.
Perennials – alfalfa,hairy indigo, redclover* Summer annuals –garden pea, mustard,turnip, barley, oats,sorghum-sudangrass Winter annuals –Austrian winter pea,hairy vetch, winterwheat, winter rye* Can be weedy in a garden settingMedium red clover*
Interplant heavyfeeders with lessdemanding crops.Peas growing vertically behind 3cauliflower plants. Growing in-frontof cauliflowers are leeks, carrotsand lettuces.
Compost tea is not thedark-colored solutionthat leaks from thebottom of the compostpile (do not spray thison food crops!) Compost tea is theextract of compostmade by suspendingcompost in a barrel ofwater (aerated orunaerated) for a shortperiod of time (up to aweek).
Provides nutrients (amounts and typesdepend upon ingredients used to make thecompost) Disease suppression (maybe?)◦ 50% less powdery mildew on grapes◦ Slight reduction of gray mold◦ INCREASE in downy mildewRodale Institute and Pennsylvania State University, recentunpublished work
Improve soilstructure Help retain nutrients Help retain moisture Improve soil aeration Lower soil pHCompost does all of these things!
Use only potable water. Sanitize all equipment. Use only compost that has maintained a tempof 131 F for 3 days (use hot compostingmethod). Must be used within 24 hours of making it. Avoid additives (esp. simple sugars likemolasses).Do not use “nutrient-enhanced” compost teas onfood crops!