Project Technical Bulletin Now Available Here!

This practical "how-to guide" provides guidance on using conservation tillage under furrow irrigation to growers, crop consultants, and public sector practitioners. This guide incorporates 4 years of field research done near Fort Collins and years of work done on the Western Slope as well as wisdom and experience of local farmers practicing conservation tillage.

 

Field Data Collection

Soil Moisture

On May 5, 2011, we collected soil samples to determine the soil moisture content for all three treaments of this project at our ARDEC field plot location. Up to the sample date, minimal moisture had been recieved for several months. Therefore, the data we obtained from the soils is very descriptive of how different tillage practices influence soil moisture.

Below is a graph showing the difference of the moisture in the first six inches of soil for both replications of each tillage treatment: Conventional Till (CT), No Till (NT), and Strip Till (ST). Units are in inches of water per foot of soil.

This data supports our hypothesis, which was that the No Till plots would contain the most moisture, followed by theStrip Till plots, and then ending with the Conventional Till plots. Similar trends were also found with samples taken from 6-12 inches, as well as 12-24 inches in each treatment.

Below is a graph of all three sample depths to demonstrate the differing moisture levels.

Field Operations

The ARDEC field site contains three tillage treatments (conventional-CT, strip-till-ST, and modified no-till-NT) with two replications. Each of these treatments are managed as though they are separate fields, allowing field conditions to dictate what needs to be done. For example, if the CT treatment needs to be irrigated, but the ST and NT are showing sufficient soil moisture we will only irrigate the two CT plots. The exceptions to this rule are for fertility, crop variety and plant population, and the removal of residue in the fall. For these issues the entire field is treated the same.

field operations 2011 field operations 2012 field operations 2013
Yield

Below shows the average grain yield for each tillage system for 2011, 2012 and 2013.

yield 2011 yield 2012 yield 2013

Figures 1-3. The effect of tillage system on average corn grain yield for the 2011 cropping season (Driscoll, 2012, preliminary data). Yield averages are based upon 12 center rows of plot.

Water Quality

Below are graphs demonstrating the sediment and nutrient data from runoff water samples we collected in the 2011 growing season. Samples were taken at the end of the row of each tillage system, and then analyzed in our campus lab.

2011 N load

Figure 1. The effect of tillage system on the Total Nitrogen load in runoff water from three irrigation events during the 2011 cropping season (Driscoll, 2012, preliminary data). Water samples were taken when water first reached the end of the irrigation furrow (0 Min) and at 120 and 240 minutes after initial runoff. Total load is the sum from the three intervals for the three irrigations.

2011 p load

Figure 2. The effect of tillage system on the Total Phosphorus load in runoff water from three irrigation events during the 2011 cropping season (Driscoll, 2012, preliminary data). Water samples were taken when water first reached the end of the irrigation furrow (0 Min) and at 120 and 240 minutes after initial runoff.

2011 sediment load

Figure 3. The effect of tillage system on the Total Sediment Load in runoff water from six irrigation events during the 2011 cropping season (Driscoll, 2012, preliminary data). Water samples were taken when water first reached the end of the irrigation furrow (0 Min) and at 120 and 240 minutes after initial runoff.

Economics

Along with other parameters, data was collected on the economics of each tillage system and then compared in different aspects such as fuel cost per acre, total cost per acre, custom rates per acre, and net income per acre. In order for any one tillage system to be truly successful it must have noted economic benefits to the producer. Below are graphs depicting economic data for the 2011 growing season.

2011 fuel cost


  Percent Savings on Fuel Compared to Conventional Tillage Percent of Total Fuel Used When Compared to Conventional Tillage
Minimum Tillage 61% 39%
Strip Tillage 55% 45%

Figure 1. Diesel fuel cost per acre for each tillage system throughout 2011. Table included with calculated percent savings on fuel when compared to conventional tillage (Driscoll, 2012, preliminary data).

2011 total cost

  Percent Savings on Total Costs When Compared to Conventional Tillage
Minimum Tillage 17%
Strip Tillage 16%

Figure 2. Total Cost Per Acre. This includes variable costs such as seed, fertlilzer, herbicides, fuel, crop insurance, etc. This also includes the fixed costs of machinery ownership. Many costs for the tillage treatments were exactly the same such as seed, fertilizer, and herbicide. Variability in costs came from fuel, machinery repair, labor, and machinery ownership. The attached table shows percent savings in total costs when compared to conventional tillage (Driscoll, 2012).

2011 custom rates


  Percent Savings on Custom Rates per Acre when Compared to Conventional Tillage
Minimum Tillage 32%
Strip Tillage 27%

Figure 3. Custom Rates per Acre. Attached table shows percent savings when compared to Conventional Tillage (Driscoll, 2012).

2011 net income

  Percent More Income Per Acre When Compared to Conventional Tillage
Minimum Tillage 19%
Strip Tillage 27%

Figure 4. Net Income per acre. This is the total revenue minus the total cost for the 2011 growing season. Attached table shows percent more income per acre when compared to conventional tillage (Driscoll, 2012).