Gardening in Nevada’s SoilsWhat is healthy soil?How does soil form?Soil has many components: – Textural or structural – Biological – ChemicalHow can you improve your soil?
Healthy soil has: Good porosity Good drainage Good water-holding capacity Good tilth, meaning they’re easy to work Lots of organic matter Lots of organisms A pH of about 7 OSU Extension Service Low salinity and sodium levels
It’s not your fault!You didn’t do anything wrong!We have very young soils geologicallyTheir youth makes them: – Highly variable both vertically and horizontally – Low in organic matter – Still a work in progress
Where do plants get their water from in the root zone? Adapted from PNW 475 by A. Miller
Soil textureSandy soil watering tips Clay soil watering tips Emitters close to the Emitters further from plant the plant Higher volume per Lower volume per hour emitters hour emitters Low duration Higher duration Increased frequency Lower frequency
Texture by feel: Sand Adapted from NRCS, Bozeman Mont. by A. Miller
Texture by feel: Loamy sand Adapted from NRCS, Bozeman Mont. by A. Miller
Texture by feel: Loams and clays Adapted from NRCS, Bozeman Mont. by A. Miller
Can you change soil texture? No, not really! Add sand to clay – mess! Add clay to sand – mess! Texture may limit your plant choices How can you improve your soil texture? – add organic matter!
Soil structure: How particles are grouped together intostable collections by organic matter “glue,” also called “peds” or soil aggregates www.statlab.iastate.edu/soils/ Platy Granular structure structure
Composition of a compacted soil Before After 50% 70% Note the reduced air space in a compacted soil.
Add organic matter to your soil What kind of organic matter? Composted or well-rotted OM OSU Extension Service
OSU Extension Service What about manure?Uncomposted manure can be high in salts(burns plants and seeds) and can contain weedseeds, diseases, and insect eggs and larva.
Erosion ControlAnother method to manage soilSoil takes time to form – you don’t want to lose it!Keep a cover on the soil – plants, mulch, etc.Provide for drainage paths and armor them to reduce the potential for erosion
Chemical Properties of SoilpH – potential of HydrogenEC – Electrical ConductivityNutrient content (plant nutrients)
pHIndicates relative acidity or alkalinitypH 7 = neutral; less than pH 7 = acid; more than pH 7 = alkaline or basic Adapted from library.thinkquest.org by A. Miller
pH – Potential of HydrogenMeasure of the amount of hydrogenNegative logarithm of hydrogen ion activity - 1 pH point is a ten-fold changepH of 7 = 1.0 x 10-7 hydrogen ions equal H+ and OH- ionspH of 3 = 1.0 x 10-3 Hydrogen ions more H+ than OH- acidicpH of 10 = 1.0 x 10-10 Hydrogen ions more OH- than H+ alkaline or basic
Soil pH and nutrients Adapted from www.soil.ncsu.edu by A. MillerWidest part of the bar indicates maximum availability
Can I change my soil pH?Not really – our soils are alkalineLimestone (calcium carbonate) buffers our soils CaCO3 + 2HCl = 2Cl- + Ca+2 + H2O + CO2 (gas)Can add sulfur, but takes time to lower pH and change is not always not permanent
EC or Electrical ConductivityMeasures how well soil conducts an electric currentSalts that dissolve in water conduct electricityPlants need some “salts” – these are nutrientsVery high EC = high salt contentIf salt contents are high, it can interfere with plant growth
Classifying salt-affected soilsElectrical conductivity measurements (EC)Exchangeable sodium percentage (ESP)Salt-affected soils are commonly classified for management purposes into three groups: saline, sodic, and saline-sodic based on EC and ESP
What to do about salt-affected soil?If you have tested and find you have salt- affected soil: – Flush the soil with water to wash the salt down below the growing zoneProblem: – High water tables, poorly drained soil and high salt content irrigation water are often the cause of or contribute to high salinity
Managing salt-affected soilsSelect plants that can tolerate salinityAvoid excess or salty forms of fertilizersIncorporate organic matterIf appropriate, add sulfur to lower the pHIf a serious problem, go to raised beds with good drainage
Plant nutrientsSubstances necessary for plant growthPlants make their own food – these are the vitamins and minerals plants need to make their food and to growExcess or improper use of fertilizers may result in plant damage and water pollutionSplit into two groups, based on the amount of the nutrients the plants need to survive and thrive
MacronutrientsN = nitrogen C = carbonP = phosphorus Ca = calciumK = potassium Mg = magnesiumH = hydrogen S = sulfurO = oxygen
MicronutrientsFe = iron Ni = nickelMn = manganese Cu = copperZn = zinc Co = cobaltB = boron Cl = chlorineMo = molybdenum
Carbon, Hydrogen, OxygenBuilding block of organic moleculesFrom the air and waterGenerally not deficient (we’d be in trouble too!)These things cycle, just like the water cycle
Nitrogen, N Constituent of amino acids, which are building blocks of proteins and enzymes. Also component of nucleic acid and chlorophyll Generally, this is the limiting factor or nutrient in plant growth. Complex cycle, since it is a big constituent of all life on the planet - atmosphere is 78% nitrogen gas or N2
Nitrogen, NDeficiency symptoms: – Slow growth, stunting, chlorosis (yellowing) – Begins with older tissues; nitrogen is mobile and moves to younger tissues (N mobile)Excess N symptoms – Excessive vegetative growth – dark green – Delayed maturity, few fruit
Visual symptoms of deficiencies: Nitrogen http://agri.atu.edu
Phosphorus, P or P2O5 Most important plant function is the storage and transfer of energy (ADP and ATP (adenosine di- and triphosphates)) Also component of DNA and plays a critical role in cell membranes Absorbed by plant roots form the soil as the ion H2PO4-1 and HPO4-2 Does not really move much in soil, just changes form, which may make it unavailable to plants – BUT will move with the soil – prevent erosion
Phosphorus, P or P2O5 Deficiency symptoms: – Slow growth, stunting, purplish or dark green color on foliage – Interveinal chlorosis (leaves are yellow on the upper surface, but remain green at the base) – Delayed maturity, poor fruit or seed development – Does move in plants, so deficiency symptoms show in the older leaves Excessive P symptoms: – Can interfere with micronutrient absorption
Visual symptoms of deficiencies: Phosphorus http://agri.atu.edu
Potassium, K Important in many plant function, such as carbohydrate metabolism, enzyme activation, and protein synthesis Essential for photosynthesis, starch formation and N fixation in legumes. As a result of these functions, a good supply of potassium produces plump grains and large tubers or roots Exists as ion (K+) in plants Helps plants adapt to environmental stresses
Potassium, KDeficiency symptoms: – Slow growth – Leaf tip and marginal burn and necrosis on older leaves – Mobile in plants, so older leaves show the deficiency symptoms – Weak stalks, small fruit, shriveled seedsExcessive K symptoms: – Light green foliage, can look like Ca and Mg deficiency
Visual symptoms of deficiencies: Potassium Corn Alfalfa http://agri.atu.edu http://ipm.iastate.edu
Sulfur:Essential for production of proteins, enzymes and vitaminsHelps in chlorophyll formationImproves root growth and seed productionHelps with vigorous plant growth and resistance to cold
Sulfur:Deficiency symptoms: – Yellowing on new leaves first, starting at tip of leaf; older leaves stay green – Sulfur is not mobile in plants, so new growth shows the deficiency symptoms – Stunted growthExcess sulfur generally not a problem
Calcium, CaEssential component of plant cell walls and membranesRegulates cell permeability and cell integrityWe have adequate Ca in our soils
Calcium, CaDeficiency symptoms: – Reduced terminal growth of shoots and roots – Symptoms show in new growth first – Ca+2 is not mobile in plants.Excess Ca+2 symptoms – Interferes with other nutrint uptake – Increases soil pH
Magnesium, MgPart of chlorophyll molecule and many enzymesAids in mobility and efficiency of phosphorus
Magnesium, MgDeficiency symptoms: – Interveinal chlorosis (leaves are yellow on the upper surface, but remain green at the base) or marginal yellowing with mid rib remaining green (tree pattern) – Marginal necrosis – Mobile in plants, so older leaves will show symptoms first (it moves to younger leaves)Excess Mg symptoms – Interferes with Calcium uptake
MicronutrientsRequired in very small amountsEssential components in enzymes, chlorophyll, DNA, etcDeficiencies are rare – generally it is the macronutrients that cause the observed problemsIron and zinc deficiencies are most common problem in our area
Iron, FeInterveinal chlorosis (veins remain green) and reduced growthCommon in our soils due to pH – iron is there, but not in a form plants can readily useNot mobile in plants, so symptoms on young leavesCertain plants more susceptible
Manganese, MnInterveinal and marginal chlorosis, but no green vein areas, as with FeExcess leads to Fe deficiencyNot mobile in plants, so effects show first on young leavesEssential in vitamin C production, citrus plants require foliar spray of Mn and Zn
Visual symptoms of deficiencies: Manganese http://agri.atu.edu
Zinc, ZnInterveinal chlorosis, decrease in stem length, rosetting of terminal leavesNot mobile, so young leaves and other terminal growth areas are affected firstCommon deficiency in many cropsExcess Zn symptoms?
Visual symptoms of deficiencies: Zinchttp://agri.atu.edu
Boron, BNot remobilized in plants, so affects new growth first and can cause death of terminal growth areas or malformed, cupped leavesRare deficiency – we more commonly worry about excess B!Excess can cause marginal necrosisGenerally, excess means soil has other problems, like salinity issues
Copper, CuDeficiency symptoms are stunted growth, poor pigmentation and death of leaf tipsAffects new growthCAUTION! Always test if you suspect Cu deficiency – Cu can be highly toxic.Excess can cause reduced growth and necrosis
Chlorine, ClRare deficiencyExcess can cause poor growth and marginal necrosis
Molybdenum, MoDeficiency similar to nitrogen – Mo plays key role in N use in plantsStunting, chlorosis, reduced yieldAffects older leaves – like N, it is mobile in plants and moves to younger growthExcess symptoms?
And last, but not least Nickel, NiMovement in soil poorly understood. Complex chemistry and forms many ionsDeficiency forms leaf tip necrosisExcess interferes with Fe and Zn uptake, chlorosis symptoms
In general…Ca and B show symptoms on terminal budsFe, Mn, S and Cu show symptoms on young leaves (not mobile in plants)N, P, K, Mg, Zn and Mo show symptoms on old leaves (mobile in plants, they will move to younger leaves)
How do we add nutrients?Minor amounts in compostMinor amounts in soil “amendments”Generally added as fertilizer
Types of fertilizersChemical fertilizersOrganic fertilizers or amendments (bone meal, compost, manure, etc.) www.farmphoto.com
Complete vs incomplete fertilizer“Complete” fertilizers contains the top 3 nutrients, like 16-16-16 general fertilizer: – Nitrogen (N) – Phosphorus (P) – Potassium (K) – 4th number, if present, is Sulfur (S)“Incomplete” fertilizers do not contain the top 3 nutrients, like Ammonium Sulfate 21-0-0
WAY TO GROW FERTILIZER What’s in the bag? 28 – 14 - 5 GUARANTEED ANALYSIS Product nameTotal nitrogen 28% NPK formula 6% Ammonium nitrogen 14% Urea nitrogen Nitrogen contentAvailable phosphoric acid 14% Phosphorus contentSoluble potash 5% Potassium content Specific sources Derived from sulfur-coated urea, etc.
A word about gypsumGypsum is CaSO4.H2OGood source of Calcium and SulfurGood for Sodium-Affected SoilsNOT a panacea for clay soils!Too much Ca can interfere with chemical balance in soil and can contribute to a magnesium deficiency and interfere with other micronutrient availability
How do I know what to add to my soil??? Test yourA. Miller soil!
What should I test for?What information does a normal soil test provide?Soil textural analysispH and saltsSoil nutrient contentFertilizer recommendationsCall your local extension office for a list of soil testing labs
Call the Lab FIRST!Find out what they test forFind out if they have package dealsFind out how much sample they want you to takeFind out how they want the sample delivered to themCall UNCE 784-4848 for list of labs
How to take a sample First, select the site. Your soil sample should represent only one soil type or soil condition.OSU Extension Service
How to take a sample Each sample should consist of sub-samples taken from about 5-15 locations within the same soil type or sampling area.OSU Extension Service
How to take a sample Use the “slice” method for a representative sample.UNCE, Reno, Nev.
How can I manage my soils to improve them?Increase the organic matter content by: • Adding compost and well-rotted manureAvoid compaction by: • Reducing tillage of wet soils • Reducing traffic on wet soils • Establish pathsMaintain cover with vegetation or mulch to reduce potential for erosionFertilize when needed