Tillage & Farming Systems Chapter 12

Objectives Historical trends in tillage Investigate reasons for tillage Different types of tillage Advantages/impacts of alternative tillage management Role of organic farming Uses & issues of transgenic crops

Purposes for Tillage Evolution of tillage: Minimum tillage in primitive times – all hand work As equipment became available – tillage increased to maximum tillage – now considered excessive & wasteful Now going back to moderate – minimum tillage – fuel savings, healthier for soil, reduced labor costs, additional technologies for control of various yield reducers, better understanding of soils

Purposes for Tillage Seedbed Preparation Most needed when planting small, high-cost seed (lettuce, clover) Less critical for vigorous, larger seeds (corn, wheat, soybeans) Should be prepared according to preference of the crop being seeded Alfalfa – fine, firm soil, shallow seeding depth Wheat – dry, aerated soil, good infiltration & aeration

Purposes for Tillage Weed Control Tillage incorporates crop residue Difficult to plant through much residue Seed may be left in residue, not in soil Seed likely to die Poor, erratic stand Weed Control Weeds compete for soil water, nutrients, light Tillage essential to deter weeds Especially before herbicides

Purposes for Tillage Today – herbicides more effective at controlling weeds than tillage Also: Eliminate field passes Preserve soil moisture Reduce damage to crop roots Less developed countries = more hand tillage/cultivation Farmers prefer aesthetically pleasing fields

Purposes for Tillage Loosening the Soil Excessive tillage can cause extensive compaction Plow or Tillage Pan – zone of compaction just below tillage zone Greatly decreased infiltration rates, aeration, root penetration Need corrective tillage to remedy, or grasslands

Purposes for Tillage Shaping the Soil Flood & Furrow irrigation Tillage forms ridges & furrows, and smoothes soil surface Allows water to move equally through field for irrigation

Purposes for Tillage Incorporation of Lime & Fertilizer Increases effectiveness and volatility of materials Control of Insects & Disease Hessian fly – plow infested wheat stubble Corn Borer – burying infests stalks Grasshoppers, etc.

Purposes for Tillage Improving Water Relations Break soil crusts, loosens soil, increases infiltration Storage of even a little more water can be difference in profitable/unprofitable yields Using subsoiler that leaves soil surface w/ little disturbance may increase water storage 3” through winter

Purposes for Tillage Aerating & Warming Compacted, crusted soils have poor air exchange Limits root growth, plant productivity Poor microbe efficiency Can speed temp warming, if desired (early spring planting) Dries soil if excessively wet What is the risk of working wet soils?

Purposes for Tillage Reasons to Reduce Tillage or Eliminate Tillage Must keep food production economical for producers & consumers Reasons to reduce tillage: Eliminate/reduce erosion Critical to keep topsoil in place for ag’s future Gov’t pressure/regulation will force more conservation techniques

Purposes for Tillage Potential benefits of reduced tillage: Save time/fuel Conventional tillage uses ~7.7 gal/ac of fuel No-till consumes ~4.1 gal/ac fuel So: 3.6 gal/ac fuel savings * $2.75 diesel = ~$10/ac * 1,000 ac farm = $10,000/yr Might this be difference in profit/loss? Potential benefits of reduced tillage: Improved air/water quality Decreased erosion Time Improved water storage in topsoil

Purposes for Tillage Double cropping more profitable Fuel Decreased compaction Soil tilth, organic matter improvements Increased wildlife habitat

Tillage Terminology Primary tillage – first & deepest tillage operation Loosens soil Moldboard plow, disc, chisel plow Secondary tillage – follow primary tillage Disks, cultivator, harrow Kill weeds, incorporate chemical/fertilizer Prepare seedbed

Tillage Terminology Chisel – narrow shank pulled through soil to rip Chisel plow – rips soil 6 – 12” depth Conservation tillage – any tillage system that leaves >30% of surface covered by residue for erosion control

Tillage Terminology Conventional tillage – traditional moldboard plow, disc, harrow, seeding Any tillage leaving <15% of surface covered by residue Coulter – disk w/ straight/fluted edge for slicing open soil Cultivator – small sweeps pulled between crop rows to kill weeds

Tillage Terminology Disk – combination gangs of concave disks to till soil Harrow – vertical tines to break clods Mulch till – surface tilled, residue remains No-till – no tillage, except for seeding & maybe fertilizer injection

Tillage Terminology Reduced tillage – combination of tillage operations >15% <30% residue cover Ridge till – ridges formed by sweeps, etc. Shovels – narrow-winged sweeps Strip till – small strips where seeds planted tilled only

Reducing or Eliminating Tillage Tillage started to improve on nature’s methods of crop growth Ability to grow more crop/land area Option to grow a single crop in a field Physical Properties of Soil Any traffic increases compaction Tillage loosens soil to depth of tillage, but increases compaction on subsoil

Reducing or Eliminating Tillage No-till – increases #/size of soil pores, soil protection & aggregation are improved w/ crop residue Reduced & conservation till fields cooler & wetter in the spring Delays planting Reduces germination & early seedling growth

Reducing or Eliminating Tillage Earthworms Improves population Greater positive effect on soil matrix Water infiltration Soil aeration Deep tillage Still feasible to help open subsoil Rip at 12 – 16” depth Deep rooted crops can also help w/ compaction & reduce tillage

Reducing or Eliminating Tillage Increases organic matter Organic matter % increases twice rate of increase in conventional till (in upper 2”) No difference in organic matter below 6” Other studies say no increase in organic matter Increased yields Are we seeing that here?

Reducing or Eliminating Tillage Seedbed Preparation Reduced till – works well for large-seeded crops Fine-seeded crops prefer more tillage, w/ pulverized, uniform seedbed May see decreased seedling emergence, reduced stand density Especially if you don’t have a planter able to get through residue May use 10-15% more seed to compensate

Reducing or Eliminating Tillage Pest Control Minimal tillage increases burden of weed control on herbicides Will increased herbicide usage delete fuel/labor savings? Maximize crop rotation effects No-till may decrease weed stands long term Don’t work weed seeds into soil during tillage Reduced ability for weed seed to germinate They need the same seed/soil contact as crops

Reducing or Eliminating Tillage Increased dependence on insecticides as well More favorable environment to harbor them Bigger problem w/ soil insects, less opportunity to disturb their life cycle What other risks are there if we depend more on chemicals for control of weeds/insects?

Reducing or Eliminating Tillage Fertilizer & Lime Applications Reduced tillage limits ability to incorporate P, K, lime into the soil Can result in a concentrated zone of nutrients in top 3” of soil May be acidified by N May cause shallow rooting

Reducing or Eliminating Tillage Organic Toxins Allelopathy – toxins emitted by one plant affected growth of another Wheat on wheat Corn on corn ? Leaving residue on the soil surface can increase the risk of toxins Most injurious in early growth stages

Reducing or Eliminating Tillage Special Situations Some crops won’t respond well to reduced tillage Have specific needs for tuber growth Potatoes Sugar beets Can be more susceptible to disease Strawberries/cucumbers & fungal diseases Excess residue problematic for surface irrigation Water not able to flow freely over soil surface Furrows need to be clean for efficient flow & help reduce erosion of ridges

Reducing or Eliminating Tillage Erosion Control Greatly decreased wind erosion w/ reduced tillage Advances in chemical technology allows for easier use of cover crops & burndown Slows ability of water to wash soil from surface as easily

Farming Systems & Environmental Quality Reduced tillage increases dependence on chemical control of pests Typically increases pesticide use 15-40% Erosion of N, P and pesticides increased w/ reduced tillage Due to zone of accumulation nearer soil surface than conventional tillage Tillage itself is erosive

Farming Systems & Environmental Quality Carbon Sequestering – putting C back into the soil Driven by global warming theory Elevated levels of CO2 Soil used to/can be source of atmospheric C w/ reduced tillage, becomes a recipient of atmospheric C

Farming Systems & Environmental Quality Water Quality Studies indicating reduced tillage reduces water pollution risks Even though more polluters concentrated at soil surface So, what else is driving this trend?

Transgenic Crops GMO’s have drastically modified farming practices & options Genetically Modified Crops Contains genes from another organism inserted artificially into a newly engineered crop RR soybeans Weed control easier, more effective w/out damaging beans

Transgenic Crops Bt Cotton Bt Corn Cotton resistant to the very damaging bollworm Insecticides often kill both damaging & beneficial insects Bt Corn Bacillus thuringensis – protein that is toxic to the corn borer Pollen from Bt corn found to be lethal to monarch butterflies Should it remain approved for use? Why?

Transgenic Crops Risks Associated w/ GMO’s Potential for herbicide resistant plant or pollen to develop Difficulty controlling escape of GMO pollen Consumer concern over GMO grain entering human food system Much debate over safety – no known health risks to humans or animals

Transgenic Crops Present Status & Trends Most countries approve planting of GMO crops Very little used in Japan, China, Europe Government concerns Backlash from religious & environmental groups Company risks Fear gov’t’s inability to enforce contracts Loss of their technology to competition

Sustainable Agriculture & Organic Farming Sustainable Agriculture – minimal use of resources (water, chemicals, energy) w/ little/no damage to environment Balance of energy used vs. energy produced Crop selection: choose proper crops for situation Crop production: proper agronomic management w/ planting, cultivating, pest management, harvest. Maximize crop rotation benefits

Sustainable Agriculture & Organic Farming Soil fertility: use legumes & manure wisely, use of commercial fertilizers sparingly, and manage their effectiveness Soil conservation: minimal tillage for acceptable field conditions Use windbreaks, buffer strips, strip cropping when necessary Minimize soil compaction Maximize crop residue use

Sustainable Agriculture & Organic Farming Objectives of Organic Farming Avoid inputs of synthetic substances Produce healthy foods untainted by unnatural substances Strategies: Use of manure & legumes for plant nutrients Tillage, crop rotation, manual labor for weed control Natural suppressants, repellants, & predators for insect & disease control

Sustainable Agriculture & Organic Farming Mixed Reviews for Organic Farming Clearly less environmental problems Although may increase N loss to groundwater Some decrease in energy use Food quality superiority unfounded 20-45% reduction in yields (European study) Increased demand for land, w/ decreased output/ac

Sustainable Agriculture & Organic Farming Organic Food Marketing Sales increasing sharply (especially in wealthy countries) Fastest growing sector of world agriculture Large export market for countries w/ highest % organic farming (Asia, Australia, Latin America) Ironic because of amount of fuel needed for transportation

Sustainable Agriculture & Organic Farming Gaining Certified Organic Status Land have no prohibited substances applied for 3 yrs before harvesting an organic crop Use of genetic engineering, ionizing radiation, sewage sludge prohibited Fertility & nutrients managed through tillage, cultivation, crop rotation, cover cropping, supplemented w/ manure (limited synthetic materials)

Sustainable Agriculture & Organic Farming Prefer use of organically grown seed Pests, weeds, diseases must be controlled through management May only use approved synthetic substances No zero tolerance standards – slight contamination (GMO’s) is allowed Restrictions also encompass food processors Livestock based organic production restrictions differ from crop production

Sustainable Agriculture & Organic Farming Four levels of organic labeling 100% organic – seal on package 95-100% organic – seal on package 70-95% organic – can claim organic, but no seal <70% organic – can list organic ingredients, no organic claim or labeling