Extended Rotations and Annual Cropping in Traditional Crop-Fallow Regions of Southeast Washington

 

 

Introduction:

During the winter of 1994-95 there was much debate and concern within the dryland farming region where we work and live. As you may recall the new farm bill had not yet been written and many felt that farm subsidies were a thing of the past. Prices were depressed and the overall mood was dismal. The concern in the air prompted us to begin to look at our options and to consider what our choices would be if, in fact, farm subsidies were totally eliminated. We quickly determined that we had several options: increase the value of our currently grown crops, increase production of our currently grown crops, substantially reduce input costs, or increase the efficiency of our cropping system to produce more and different saleable crops on the same acres. After considering several possible options we decided to begin to look at ways to try to increase gross profit per acre by looking at different rotational options in order to maximize our soil and water resource efficiency. Our search for ideas quickly led us to research that had been conducted at the Pendleton Research Station in earlier years to look at the efficiency of summerfallow for trapping and storing moisture. It is there that we began to look at possible alternatives to our traditional wheat/summerfallow system that would provide us better efficiency with our water resource and more gross profit per acre on our farms.

The Pendleton Study:

In 1978 researchers at the OSU Pendleton Research Center began a study to monitor three different summerfallow systems in three different rainfall regions for their efficiency in moisture capture and storage over the summerfallow period. Their study looked at an 18 month summer fallow cycle from August immediately following harvest, through the first winter with the ground laying idle, then the summer months preparing and maintaining the summerfallow, and then the second winter after seeding a new winter wheat crop, ending in February. The study compared three systems for preparing summerfallow in three different locations and over four different 18 month periods.

The results were astonishing across all treatments and geographys. The research revealed that an average of less than 40 % of the rainfall that occurred during the 18 month cycle was actually captured as available moisture by the end of the 18 month period. However what was even more astonishing was the fact that over 75% of that moisture was already present in the soil profile after just the first winter following harvest and the additional 12 months of summerfallowing the soil only netted an additional 2-3 inches of available soil moisture. The summer months actually yielded a net loss of 1-2 inches regardless of the rainfall and the second winter was much less efficient at capturing rainfall than was the first. The inefficiency of the summerfallow process in capturing and storing soil moisture was evident in all three locations and under all three management systems. The Pendleton site which more accurately represents our area had only a 36% moisture efficiency in the study for the summerfallow period and over 80% of the total available soil moisture present at seeding was available after the first winter (Table 1).

Table 1. Effect of wheat stubble management in a fallow-wheat rotation on the conservation and storage of water at three locations in Oregon. Data are the average of four fallow-wheat cycles, 1978-1980 through 1981-1983.

 

Local Soil Moisture Data:

After reviewing the OSU data we decided we needed to compare the findings collected there to data generated in our area. We reviewed our soil test data and located a field that had been routinely soil sampled each spring in both the standing wheat and in the adjacent stubble acres to be summer fallowed. These tests had been taken for many years. By using these soil tests we were able to compare soil moisture from one spring to the next after just one winter of moisture capture and then again after a summerfallow period and a second winter of moisture capture. We were astonished to find that our own data supported the Pendleton data. In fact our local data was almost identical to the data that had been collected at the Pendleton plot location. From 1991-1997 our soil tests revealed that over 82% of our available soil moisture was present after just the first winter and that an additional 12 months of summer fallowing yielded us, on average, approximately 1.64 inches of additional soil moisture in our 16 inch rainfall area (table 2).

 

Table 2. Soil moisture data for Waitsburg / Dayton, WA area, a 16-18" rainfall zone.

 Year

 1st Spring

 2nd Spring

 + or -
 1990-91  8.93 in  11.52 in  2.59 in
 1991-92  8.05 in  9.22 in  1.17 in
 1992-93  8.35 in  8.37 in  0.02 in
 1993-94  5.87 in  12.72 in  6.65 in
 1994-95  10.93 in  11.72 in  0.79 in
 1995-96  11.81 in  11.72 in  -0.09 in
 1996-97  11.88 in  11.50 in  -0.38 in
 1997-98  8.80 in  11.40 in  2.40 in
       Average 1.64 in

Tim Try Anything:

After convincing ourselves that the data collected in the Pendleton study did actually correlate to data from our own area we began the task at looking at our options for taking better advantage of the our rainfall and reducing summerfallow. We put together several grower presentations using a make believe farming operation owned and operated by a fictious producer named Tim Try Anything. Using Tim’s 1000 acre farm we plugged in several different rotational ideas and did our best to predict the outcome using our best estimates of input costs, moisture requirements, rotational benefits, and estimated yields for our area.

The results of the rotational comparisons revealed that when summer fallow was reduced and the agronomic benefits of extended rotations were included, the farm gross profit per acre began to rise. With minimal, if any, yield benefit from the summer fallow process, the added income from more of the farm producing rather than draining operating capital began to show tremendous benefit over time. This was true even in dry years. In addition, input costs for producing winter wheat decreased due to the decrease in disease and weed pressure in a longer rotation.

Looking at Spring Crops:

After convincing ourselves that summerfallow was a very inefficient system and that having 50% of our farm acres involved in this practice did not make sense economically, we set out to identify ways to reduce acres dedicated to this practice. With a limited number of crops suited to our particular climate and topography our attention quickly turned to the need to successfully incorporate the use of spring crops in our systems in order to extend rotations and reduce summerfallow. Since spring crop experience in our area was limited and traditionally not very successful, we felt we needed to begin an experiment to demonstrate the true potential of different spring crops in our area. Our contention was that poor spring crop experiences in the past were due mainly to poor management of both fertility and soil moisture. We felt that by eliminating many of the factors that had limited spring crop yields in the past, we could begin to evaluate each spring crop’s real potential to contribute gross profit per acre.

 

Spring Crop Rotation Study

Dick Jones - Dayton Washington

 

This experiment was conducted near Dayton Washington in a 16.5 inch rainfall zone. The traditional rotations in this area are winter wheat/summer fallow or winter wheat/spring barley/summer fallow.

The purpose of the plot was to give growers in this area as well as growers in similar rainfall zones with the same rotations, better economic and agronomic information as to the production of spring crops in their area and to evaluate the differences between them. This would provide growers who were interested in extending their rotations more realistic information and expectations.

We began this experiment in the spring of 1995. The study was designed to evaluate the yields and economic returns of the four spring crops we chose to study in this rainfall zone. We established the following crops and rotation sequence.

 

Fertility, disease, residual herbicide carryover, and potential crop contamination were all factors in determining the sequencing of the rotation. This is a large scale experiment so grower owned and commercial sized equipment was used in all phases of production. In addition, each treatment was replicated four times to eliminate variability.

Year one - 1995

Procedures

We began the experiment in the spring of 1995 following a 80 bushel winter wheat crop. We selected a uniform site and took soil samples to determine residual nutrients. The stubble had been left standing over winter. Eight ounces of Roundup RT was applied in late February and the volunteer allowed to dry down. The field was burned on March 20 and fertilized on March 27 with a RipperShooter®. The field was cross cultivated and needed on March 30. The Canola plots required an additional harrowing to produce an acceptable seedbed.

 

Year 2, 3, and 4

Tillage Procedure Recap

1996 - 1997 - 1998

 

In year two the stubble crops from our first year’s spring crops were left standing over winter. Fall rains initiated a flush of volunteer necessitating both a fall and spring application of roundup RT to control the "green bridge." The residue in the wheat and barley plots was burned in late March. All of the plots were fertilized with a Ripper Shooter® on April 5th. The field was then cultivated and seeded on April 6th with the grower’s John Deere 8200 drills.

Year three:
The continued evolution of the two pass system:
The stubble crops from the previous spring crops were left standing after harvest and over winter. Very little volunteer grew over winter, so a single spring application of Roundup RT was applied in early March. Burning of the cereal residue was limited to only parts of each plot. A twenty foot non-burn section was left in front of two of the four reps. This allowed us to evaluate stand establishment in non-burned standing stubble.

In the past we had followed theRipper Shooter® application with a cultivation, and then seeded with conventional John Deere 8200 drills. This year we eliminated the cultivation and seeded directly following the Ripper Shooter® with a set of John Deere unifold 455 drills. Seeding was conducted on April 5th. Cool temperatures and pounding rains followed, preventing us from obtaining an adequate canola stand. We re-seeded the canola directly into the existing stand on April 28th with the JD 455 drills.

Year four:

Additional modification of the two pass system: Success in establishing the spring crops using little or no burning, and the newer generation of high residue grain drills was encouraging and led us to utilizing this practice exclusively the fourth year of the study. The stubble crops from the previous spring crops were left standing after harvest and over winter as before. Once again, fall rains allowed us an opportunity to use both a fall and spring Roundup application to control volunteer and weeds. We fertilized to a depth of six inches with a Ripper Shooter®directly into the standing stubble on March 25th. The crops were seeded with the John Deere unifold 455 drills on the same day. We were very pleased with stand in all of the replications.

 

Crop Protection Summary

 

Each year we sprayed the weeds and insects as we felt necessary. Each different set of environmental conditions produced different weed and insect spectrums. We made all necessary applications for each individual crop each season to try to maximize net return. All inputs including application costs were recorded. A complete and detailed listing of all input costs is provided in the McGregor Company’s Research Compendiums from 1995 - 1998.

 

Soil Sample, Yield Goal, and Fertility Summary

In year one the entire plot area was soil sampled for residual nutrients. Organic matter mineralization was predicted and yield goals for the four crops were calculated. From these figures we were able to set predicted yield goals and the associated fertility rates for each crop.

Following year one, it was necessary to sample each individual plot separately to obtain specific post harvest residual nutrient levels. Based on the individual plot soil samples, and the previous crop’s residue levels, we were able to determine nutrient requirements for the following crop.

Yield Goals: From our soil samples we made yield goal predictions and fertility recommendations. (see McGregor compendium for complete details) The averages over the four year study is as follows:

Soft White Spring Wheat Spring
Canola
Hard Red Spring Wheat Spring
Barley
 Ave. Yield Goal  65 bushels  2000 lbs  60 bushels  4750 lbs
 Ave. Fertility  87N/11P/11S 100N/6P/19S  136N/11P/11S  125N/11P/11S
 Ave. Cost/Acre  $35.95  $40.00  $49.73  $46.90

 

Spring Crop Comparison Study

Four Year Average

 

   Soft White Spring Wheat  Spring
Canola
 Hard Red Spring Wheat

 Spring
Barley
 Total Inputs**  $77.45  $96.00  $87.94  $129.27
 Yield  61.95 bu/ac  58.4 bu/ac  4570#/ac  1532#/ac
 Market Price  $3.93/bu  $4.46/bu  $95.15/ton  $ .1079/lb
 Net Dollars/ac  $167.23  $163.51  $132.16  $29.86

** Does not include tillage and harvest costs
Crops were sold August 31 each crop year

 

Conclusions

 

Many useful and significant observations were made during the four years of this study.

First was the confirmation using our own soil testing data that a traditional winter wheat - summer fallow rotation in intermediate rainfall zones is very inefficient at storing and utilizing available moisture. With out a doubt much of the annual precipitation in these regions can be used for crop production, but is lost in a strictly wheat-fallow system.

Secondly, the establishment of spring crops in intermediate rainfall zones can be done very effectively and is accomplished by leaving stubble stand over winter for maximum water storage. Our evolving process for minimizing the trips across the field in the spring used to establish the spring crop also allowed us to keep more soil moisture for spring crop production.

Thirdly, soil testing prior to fertilizing to determine proper rates for realistic yield goals and utilizing equipment capable of placing fertilizer to a depth of 5 to 6 inches deep is essential to keep fertilizer available for spring crops. Traditional spring crop fertility rates in our region were insufficient to meet the higher yield goals we were able to obtain with better soil moisture management.

Fourth we are confident that we can consistently establish and produce successful spring crops using the McGregor Direct Seeding System (two pass) for crop establishment in the spring. Much of this region’s poor experiences with spring crops can be traced to over working the soil in the spring, fall tillage that reduced winter soil moisture capture and storage, and inadequate fertility.

Lastly, extended rotations in the 16 inch and higher rainfall areas of our region are desirable and more profitable that traditional wheat-fallow rotations. Farms in these regions benefit little from having tracts of arable acres sitting idle in a fallow system.


 

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