Evaluating Soil Resources & Pasture Fertility

Transcription

1 Evaluating Soil Resources & Pasture Fertility John Hobbs Agriculture / Rural Development Specialist Pineville, MO Adapted from a presentation by Dr. John Lory

2 Outline Soils Nutrient cycling hay vs. pastures Manure distribution in pastures Cow-pie bingo explained Interpreting soil test levels The lowdown on low testing soils Making fertilizer pay Fertilizer pays sometimes Soil sampling pastures A little knowledge goes a long way

3 Soil - From the Latin word solum means land or ground The word soil has many meanings Soiled dishes or clothing A pollutant such as dust or sediment in water

4 Soil (2) Is the natural body in which plants grow (effects plant community) An engineer looks upon the soil as a material which supports foundations and highways A resource to collect water, waste disposal or recreation IN GENERAL, soil refers to the loose surface of the earth as distinguished from solid rock

5 Components of Soil Ideally 50 : 50 Pore Space to solids Mineral Inorganic Aluminum, iron, silicon, calcium, etc. Organic living and dead Water Air Minerals 45% H 2 O 25% Organic matter 5% Air 25%

6 Soil Nomenclature/survey O - Organic matter A - Topsoil B - Subsoil C - Parent material R Bed rock

7 Soil Development There are 5 major factors that are responsible for the kind, rate and extent of soil development Climate: the most influential factor Living Organisms Parent Material Topography Time

8 Climate High average temperatures and precipitation encourages rapid weathering and clay formation Soil development is slow where the climate is warm and dry, cold and dry or cold and moist

9 Living Organisms Beneath the soil surface is a land of mystery. Strange creatures have found ways to survive in a world without sunlight Life in the soil is diverse, ranging from microscopic single-celled organisms to large burrowing animals

10 One teaspoon of soil contains 100 million bacteria 800 feet of fungal threads

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12 Parent Material Mineral or organic matter from which soils are developed Loess - wind blown, (dust storms) Alluvial - water deposited Glacial Material Volcanic ash Bedrock - limestone, shale or sandstone Colluvium, deposit at base of slope

13 Limestone

14 Topography How the land lays Hills, ridges, valleys, drainages Is important to forage species Fence and pipeline locations Facilities Livestock movement Lanes and crossings (Flat = mud and steep = erosion)

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16 Time 100 years or thousands of years

17 Soils - why are they important to your Grazing System (1) Serves as the rooting medium plus water and nutrient storage for plants Soil quality effects the vigor and health of your plants Determines the type of forage species that are adapted or that you can grow well (wet, well drained, shallow to rock or hardpan) Estimating forage yields (grazing or hay)

18 Soils and Topography- why are they important to your Grazing System (2) Sizing your paddocks (size according to yield) Drier shallower soils on south facing slopes will warm up faster in the spring and be ready to graze first North facing slopes are deeper soils and more moist (more productive)

19 Soils and Topography - why are they important to your Grazing System (3) Selecting paddocks that are well drained during wet periods (reduce compaction) for grazing or calving Placement of and construction of lanes, ponds, water tanks and fence Stream Crossings and Flood Gaps Dollars, planning and time increase with increased complexity of topography

20 Excessive Chert or Flint

21 Ozark Soils Many developed under forestland conditions. They are older soils with strong development, highly leached, acid and have a high clay content Claypan - inhibits root growth, is strongly acid, hard when dry and sticky when wet (Prairie soils) Fragipan - inhibits root growth, very acidic (aluminum), droughty but wet in spring, mainly on flatter ridges

22 Ozark Soils 2 Many soils have a high percentage of rock fragments and/or shallow depth to bedrock are low in natural fertility, organic matter, calcium and available phosphorus well suited to both cool and warm season grasses or woodland Some soils are well suited to small grains or warm season annuals

23 A reflection of soil type or management? BROOMSE DGE TALL FESCUE

24 Farm Nutrient Management Inputs Nutrient Cycle Exports - fertilizer - manure - legumes (N) - hay - animals - nutrient losses

25 Hay System Inputs Nutrient Cycle Exports - fertilizer - manure - legumes (N) - remove 80% of nutrients in hay 3 tons of hay remove: lb. nitrogen - 18 lb. P (40 lb. P 2 O 5 ) lb. K (145 lb. K 2 O)

26 Pasture System Inputs Nutrient Cycle Exports - fertilizer - manure - legumes (N) - feed - calves - beef Cow/calf pair, stocker removal rates - 10 lb. nitrogen - 3 lb. P (7 lb. P 2 O 5 ) lb. K (1 lb. K 2 O)

27 Phosphorous Cycle Pasture system Export - calves - beef Feces and urine Losses - erosion - runoff Plant available soil P

28 Phosphorus Cycle Pasture system Forage 29 lb. P Retained 3 Excreted 26 lb. P Efficiency 90 % returned

29 Nitrogen Cycle Pasture system Export - calves - beef Feces and urine Losses - nitrates - erosion - runoff Plant available soil N

30 Nitrogen Cycle Pasture system Forage 280 lb. N Retained 10 Excreted 270 Volatilization 70 to 135 Returned 200 to 135lb. N Efficiency 50 to 70 % returned

31 Excretion by livestock Dairy Steers Urinations / day Urine volume (qt) Urine N (lb. / mo.) Defecations / day Fecal N (lb. / mo.) (Whitehead, 1996)

32 Facts of Nutrient Management for Grazing Systems Low P and K removal monitor with soil testing Nitrogen losses necessitate annual inputs if legumes are not present

33 Manure Distribution Continuous grazing versus MIG MIG improves manure distribution Missouri research compared 3, 12, and 24 paddock systems

34 Manure Distribution

35 Manure Distribution Continuous grazing Grazing area Animal consumption Loafing area Animal excretion Feces and urine Plant available soil P

36 Manure Distribution Rotation Frequency Continuous 14 day 4 day 2 day Years to get 1 pile / sq. yard

37 Interpreting Soil Test Results Low Yield loss likely Forage quality reduced Medium Yield loss possible Improved persistence High Benefits from fertilization unlikely

38 Characteristics of low fertility soils Reduced yield Reduced forage quality Dependent on fertilizer N Reduced persistence of desirable species

39 Soil Test Level for Persistence Alfalfa Annual lespedeza Red clover White clover Cool-season grass Warm-season grass Very low Low Medium High

40 Low ph s (below 5) Increased aluminum solubility stunted root growth reduced nutrient uptake Reduced nutrient availability phosphorus Poor legume growth survival and activity of N fixing bacteria reduced reduced success of the symbiosis

41 Low phosphorus Poor crop growth critical for energy conversions in plant affects all aspects of growth Poor root development Poor legume growth reduced survival and activity of N fixing bacteria

42 Low potassium Poor crop growth inhibition through reduced enzyme activity impaired water uptake Reduced disease resistance Reduced winter hardiness

43 Making Fertility Pay Maximize forage utilization. Invest in fertility where you expect the biggest benefit. The higher the value of your product, the better the return on fertility investments.

44 Fertilizing on a Budget lime first target very low and low testing soils even low rates (20 lb.p 2 O 5 /acre) on fescue reduces grass tetany manure can be an excellent fertilizer

45 Fertility Management Strategies Grass/legume mixture ph P and K at least medium No fertilizer N Spring vs. Fall N only apply spring N if you are short on spring pasture or are haying apply lb./acre in August for stockpiling

46 ph Management history influences soil test Rowcrop field 3 Rowcrop field 2 Rowcrop field 1 Pasture Limestone road

47 Management history influences soil test Rowcrop field 3 Rowcrop field 2 Bray-1 P lbs P/acre Rowcrop field 1 45 Animal feeding Old homestead 30 15

48 Obtaining a good soil sample cores at random points along a zig-zag pattern in the field Avoid sampling near feeding areas and shade trees in pasture x x x x x x Avoid sampling near road x x x x x x x x x x

49 Obtaining a Quality Soil Sample (cont.) Sample 6 to 7 inches deep in the soil Take a uniform quantity of soil from each depth If using a shovel dig a hole and slice off one side After collecting all cores in a bucket - crumble the soil into small pieces and mix well. Place about 1.5 cups in a soil sample box. Discard excess soil. Label the box with the farm and field name.

50 Soil Sampling Devices T-probe tube. Cost: ~$30-50 Step probe (fixed). Cost: ~$65 Screw auger s/ T-bar. Cost: ~$ Back-saver probe. Cost: ~ $350

51 Soil test P (Bray-I, lbs./acre) Soil test data from one core is highly variable Mean: 44 STD: Core number

52 Soil test P (Bray-I, lbs./acre) Accuracy can be increased by dividing fields based on known variability Pasture Old manure piles Core number Feeding areas Overall Mean: 44, STD: 48 Pasture mean: 20, STD: 17 Feeding area mean: 114, STD: 52

53 Grazing doesn t create fertility It just rearranges it!

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