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Best Management Practices in Ecofallow No-Till Sorghum

 

Best Management Practices in Ecofallow No-Till Sorghum

By Charles Ikard

Advantages

Nebraska research specialists define ecofallow as controlling weeds during the fallow period by using herbicides and/or tillage with minimum disturbance of crop residues and soil. This concept has been used for over 20 years. Ecofarming is defined as, a system of controlling weeds and managing crop residues throughout a crop rotation with minimum use of tillage. This technique is used to reduce soil erosion and production costs while increasing weed control, water infiltration, moisture conservation and crop yields. No-till sorghum fits well within an ecofarming system.

Ecofallow helps maximize soil water storage. Maintaining crop residue cover is important to increasing stored soil moisture in the following three ways:

  1. Reducing run off
  2. Increasing soil infiltration
  3. Reducing evaporation

Scientists from Kansas State University report rain falling on bare soil can seal off the soil within the first 30 minutes, depending on soil texture and rainfall intensity. As little as one half inch of rainfall can seal the surface of bare soil.

Snow trapped in sorghum field residue.

When the soil surface becomes sealed, infiltration slows or ceases and water begins to run off. Surface residue slows runoff and can increase the available time for infiltration by two to threefold. Soil residue, especially standing stubble, provides an added benefit in trapping snow. In western Kansas, moisture from snow can add 1.6", in an area where soil water available to plants from rainfall is only about 2.5" (10" rainfall during growing season and 25% efficiency). The University of Nebraska reports trapped snow can result in one to three inches of additional water being available for crop production, making snowfall an extremely valuable source of soil moisture. Tillage regularly results in significant soil moisture losses. Data from Colorado shows soil water losses from different tillage operations in Table 1.

Table 1: Water losses per acre following various tillage practices.
Tillage Operation1 day after tillage4 days after tillage
Disc 0.33" lost 0.51" lost
Chisel 0.29" lost 0.48" lost
Sweep Plow 0.09" lost 0.14" lost

Crop Rotation Considerations

Evaluating yield results from multiple locations, two conclusions can be made.

  1. Wheat yields were slightly lower in wheat-sorghum-fallow (WSF) than in wheat-fallow rotations (WF)
  2. Continuous sorghum yields were lower than WSF sorghum yields

If over 3 feet of soil moisture is available, sorghum can be successfully planted following a previous sorghum crop. A good management approach is to probe for soil moisture before planting.

Growing Wheat Under Ecofallow Management

Plant wheat seed that has been professionally cleaned to provide good germination and stand establishment, to help reduce weed competition. Planting in narrow rows will provide ground cover more quickly, but drills with wider spacing may produce better stands under dry soil conditions. Check wheat fields in early March and spray broadleaf weeds if necessary. Use a straw spreader on harvesting equipment to distribute straw evenly rather than in rows. Spray weeds with a burn-down herbicide after wheat harvest.

Field probe - Sorghum

Note use of six foot probe in the foreground.

Residue Management

Residue covering 20% of the soil surface can reduce erosion by 50% compared to soil with no covering. Residue on 40 percent of the soil surface can reduce erosion by 75% compared to bare soil.

Fertilization of Winter Wheat

Proper fertilization is essential for good grain and straw yields. Use soil tests to determine fertility plans for desired yields. Phosphorus is very important in winter wheat, as adequate fertility makes the crop more competitive with winter and spring weeds. Dual injection of anhydrous ammonia and phosphorus in 12-inch spaced bands is an effective pre-plant fertility method. Avoid top dressing when soil is wet or soil compaction will result. Ecofallow used with No-Till increases soil moisture.

The following data tables show advantages of tillage methods for increasing soil moisture to following crops.

Table 2. Fifteen-year soil moisture results from various tillage methods in Akron, Colo.
YearsTillage SystemNumber of Tillage PassesAnnual RainfallFallow Water
1916-30 Plow 7-10 17.3" 4.0" Storage
1931-45 Disk Conv. Till 5-7 15.8" 4.4" Storage
1946-60 Improved Conv. Till 5-7 16.4" 5.4" Storage
1961-75 Stubble Mulch Min Till 2-4 15.3" 6.2" Storage
1976-90 Min Till to No-Till 0-2 16.2" 7.2" Storage
Table 3. Comparative yield values of 2 crops from 1" of soil moisture at various dryland locations
(Water Use Efficiency - lbs./acre/inch)
LocationWheatGrain Sorghum
Tribune, KS 144 lbs. 280 lbs.
Garden City, KS 163 lbs. 290 lbs.
Walsh, CO 118 lbs. 215 lbs.
Bushland, TX 87 lbs. 216 lbs.

Getting Started in Ecofallow

Starting an ecofallow system requires determining a desired crop rotation. Options include wheat-fallow (WF), wheat-sorghum-fallow (WSF), or continuous sorghum (SS) rotations.

Kansas State University research shows wheat fallow did not return enough to cover expenses without government payments. Their data also shows WSF rotations will return a profit without government payments and with less relative risk than WF rotations. Continuous sorghum and WSF systems were most profitable in Texas.

The following graphs show grain yield results from different locations in the Great Plains under various crop rotations.

Comparison wheat/sorghum yields - TX
 
Comparison wheat/sorghum yields - Garden City, KS
 
Comparison wheat/sorghum yields - Hesston, KS
 

Fertilization of Grain Sorghum

Starter fertilizer is important in no-till cropping due to potential cool soil conditions at planting and the difficulty of incorporating this into the soil. There are a number of benefits from starter fertilizer, such as increased early growth and more uniform plant development. University of Nebraska data shows yield increases from starter fertilizer are more dramatic in soils testing low in phosphorus (15 ppm or less). Kansas State University researchers evaluated starter fertilizer (30-13-0) and determined adequate applications hastened sorghum maturity by six days.

Weed Control

Weed control is critical in ecofallow cropping systems to help prevent the loss of soil moisture to non-crop plants.

Table 4. Water use by various plants under dryland farming conditions.
CropWater Use
Pigweed 287 lbs. water used / lb. dry matter produced
Sorghum 304 lbs. water used / lb. dry matter produced
Corn 349 lbs. water used / lb. dry matter produced
Wheat 528 lbs. water used / lb. dry matter produced
Lambsquarters 801 lbs. water used / lb. dry matter produced
Ragweed 948 lbs. water used / lb. dry matter produced

Weed control basics – wheat-sorghum-fallow rotation after wheat harvest:

  • Glyposate and dicamba can be applied to wheat stubble after harvest, but must have the correct surfactants or ammonium sulfate added, as required by product labels
  • Fall application on wheat stubble of atrazine, glyphosate and/or dicamba
  • Spring pre-plant application of glyphosate and/or dicamba, with grass control requiring a herbicide such as metolachlor, alachlor or dimethenamid, which must be used in conjunction with herbicide safened sorghum seed.
  • Weed control basics – wheat-sorghum-fallow rotation after sorghum harvest:
  • Glyphosate and/or atrazine can be used after harvest, with necessity determined by the level of weed control on the sorghum crop before harvest
  • Roundup or Landmaster-BW in the spring to control summer weeds
  • Light tillage may be helpful/necessary before planting wheat if residue levels are too heavy for adequate seed-to-soil contact

Hybrid Selection

Early seedling vigor is important for successful no-till sorghum. Most Pioneer grain sorghum hybrids have excellent early growth and are suitable for no-till planting. Color score is important for later plantings. Higher color scores represent better hybrid maturity in cool weather.

Planting Date

Planting dates are defined by geography and weather patterns. Later maturing sorghums generally have higher yield potential than shorter-season hybrids. Adequate soil temperature and moisture are essential for developing a good early stand. A general rule of thumb is to plant sorghum about 2 weeks following the ideal time of corn planting in a given area. Soil moisture can be checked by probing the soil with a 6-foot metal penetrometer, just prior to planting. Yields can be maximized by planting a hybrid that will head during the wettest part of the growing season.

Planting Rate

Sorghum has the ability to compensate well for low seeding rates and will tiller to fill in open spaces. However, low seeding rates can improve the ability of sorghum to better tolerate drought conditions. With precision row-crop planters, lower seeding rates are easily achieved, while planting with a drill usually results in over-planting and is not recommended.

Yields of over 8,000 pounds per acre (143 bushels) are possible with seeding rates as low as 30,000 seeds per acre (recommended low seeding rates vary in different regions). Make sure good quality, high germination seeds are used when planting reduced rates of sorghum.

Always plant based on seeds per acre and not pounds per acre. Sorghum hybrids can vary from 12,000 to 16,000 seeds per pound and if planted by weight could produce populations too high for optimal crop growth. Sorghum may also lose staygreen and not head under drought stress when plant stands are too dense. Thick stands result in smaller diameter stalks, which under most growing conditions will contribute to increased plant lodging.

Sorghum seed size comparisons

Seed size may differ between lots based on growing conditions or simply by hybrid

Soil Temperature

Sorghum requires higher soil temperatures for germination and emergence than corn. Best germination is obtained when the soil temperature is 65 F and above. Sorghum is frequently planted at lower soil temperatures and will do relatively well if seedling vigor is strong. Data from Colorado indicates soils with 3,000 pounds per acre of residue are typically from 8 to 10 degrees cooler than bare soil. Table 5 shows reduced stands in no-till sorghum had no effect on grain yield.

Table 5. Effect of different tillage methods of sorghum stand establishment

TillageFinal StandGrain Yield in Bu.Grain Yield in Lbs.
Conventional Tillage 89,633 Seedlings/A. 94.47 Bu./A. 5,290 Lbs./A.
No-till 78,067 Seedlings/A. 94.35 Bu./A. 5,284 Lbs./A.

Conventional tillage involved 10 trips including harvest. No-till had 5 trips including harvest. Three year study from Temple, Texas (rainfall from 12" to 20").

Insects

Cruiser 200 insecticide applied as a seed treatment provides good control of soil insects and early-season pests. Scout fields throughout the growing season for insect populations that may reach economic thresholds later in the growing season.

Diseases

Stalk rots can be a common occurrence in dryland sorghum production because of the stressful growing conditions. Management practices of planting hybrids with good tolerance to stalk rot and using moderate seeding rates for expected in-season soil moisture conditions help prevent stalk rots. No-till sorghum is usually under less moisture stress than conventional sorghum due to enhanced moisture stored in the soil. In a 3-year test in Nebraska, stalk rot was reduced by 28% under no-till management and grain yields were higher than conventional-tilled sorghum.

Summary of Best Management Practices

  • Control weeds with careful selection of pre- and post-emergence control options.
  • Check soil moisture to help choose which spring crop to plant.
  • Select crop rotations that have the highest chance for economic returns in the area.
  • Fertilize for realistic yield goals and consider starter fertilizer to boost crop performance.
  • Maximize water storage and soil infiltration rates with no-till techniques.
  • Control pests with insecticide seed treatments and season-long crop scouting.
  • Harvest with the next crop in mind.
  • Use as stalk spreader/chopper to distribute crop residue evenly.
  • Manage residue for maximum water storage.
  • Winter moisture enhanced by standing crop residue can be invaluable in maximizing returns in the second crop year.

Charles Ikard began with Pioneer Hi-Bred in 1975 as an agronomist and is currently enjoying retirement. He holds a Bachelor of Science degree in agricultural engineering from Oklahoma State University and. has more than 40 years of experience growing and evaluating sorghum.

References

  • Conservation Tillage Research. 1994. Report of Progress 705. Kansas State Univ.
  • Cropping and Tillage Systems for Dryland Grain Sorghum USDA. ARS, Conservation and Production Research Laboratory, Bushland, Texas Report Number 93-10 (1993)
  • Dryland cropping systems in Eastern Colorado. Colorado State Univ. 0.516
  • Ecofarming: No-Till Sorghum Following Ecofallow Corn or Sorghum. Univ. of Nebraska - Institute of Agriculture and Natural Resources.
  • Ecofarming: Selecting Corn and Grain Sorghum Hybrids, and Planting Dates, and Planting Rates in a Winter Wheat-Row Crop-Fallow Rotation. Univ. of Nebraska - Institute of Agriculture and Natural Resources.
  • Fallow aids in Winter Wheat - Fallow Rotation. Univ. of Nebraska - Institute of Agriculture and Natural Resources.
  • Field Research.1996. Report of Progress 762. Kansas State Univ.
  • Getting Started in Ecofarming Growing the Winter Wheat Crop. Univ. of Nebraska - Institute of Agriculture and Natural Resources.
  • Grain Production and Economic Returns from Dryland Sorghum in Response to Tillage Systems and Planting Patterns in the Semi-Arid Southwestern USA. Journal of Production Agriculture. 249-256.
  • Grains and Oil Crops - No-Tillage Grain Sorghum Response to Starter Nitrogen-Phosphorous Combinations. Journal of Production Agriculture 8:369-373
  • Great Plains Dryland Conservation Technologies. Kansas State Univ. May 2004.
  • Managing Corn and Sorghum Residues During the Ecofarming Fallow Period. PDF Univ. of Nebraska - Institute of Agriculture and Natural Resources.
  • Precipitation Use Efficiency as Affected By Cropping and Tillage Systems. Journal of Production Agriculture. 9(2)
  • Southwest Research Extension Center. Report of Progress 712. Kansas State Univ.
  • Tillage Intensity Effects on Corn and Grain Sorghum Growth and Productivity on a Vertisol. 1996. Journal of Production Agriculture. 385-390
  • Using Starter Fertilizers for Corn. Grain Sorghum and Soybeans . Univ. of Nebraska - Institute of Agriculture and Natural Resources (
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