Posts from the Archive: The Goal and Objectives of Good Irrigation Management.

Sometimes you stumble on some old work and say,  wow did I write that?   Below are some thoughts on the benefits of good irrigation scheduling.

Perhaps the most misunderstood, over looked, and under utilized practice in crop production systems today is proper irrigation scheduling; it encompasses the most critical input, water. Water is the catalyst for many phyto-chemical reactions within the plant that are necessary for the plant to obtain optimal health.  Below is the rational and legitimacy of irrigation scheduling.

GOAL:

Irrigation scheduling should be utilized as a mechanism to respect the water consumption needs of plants through their various growth and developmental stages in order to attain high yields while maintaining soil quality and conservation of water.

OBJECTIVES:

1.  Target soil moisture depletion percentages should be utilized by to schedule the irrigation of fields.

2.  The “feel” method and other technologies should be used to properly monitor soil depletion levels.

3.  The calculation of moisture loss should be equated by utilizing evapo-transpiration in accordance with the modified penman equation and crop coefficients.

4.  Improve uniformity of irrigation applications by calculating flow rates and application efficiencies of the irrigation system being utilized.

5.   Influences such as moisture holding capacity, knowledge of the plant root depth, soil texture, salinity, and organic matter should be considered when determining plant available water.

6.  Improve soil absorption and pecolation efficiencies in order to properly leach accumulated salts through, and past, the root-zone profile by properly quantifying the target moisture level in the root profile and the amount of water to be applied.

7.  Critical growth stages should be considered and irrigation should be utilized to improve crop quality.

8.  Mitigation of ground water pollution from fertilizers by increasing plant root depth and allowing proper moisture transport through the soil profile and optimizing nutrient management.

Proper irrigation scheduling is vital in order to optimize plant and soil interactions.  Water plays important roles in many facets of not only plant health, but also in soil fertility.  That being the case, quantifying the amount of water and the time between irrigations has a direct affect in the quality of a crop.

Alfalfa Irrigation, the last kiss before the cutting.

Good alfalfa production depends on good irrigation scheduling in the desert.   The most critical irrigation is the one prior to the cutting.  Fields that lack sufficient water for good regrowth after the cutting suffer significant yield losses.    Each day a cutting is delayed after an irrigation is worth 4 days in the windrow for curing (1.4 Kc vs 0.3 Kc).    Below is a table to assist local growers in estimating the minimum time needed for the soil to be sufficiently dry to swath the field.

Cutting Trends in Desert Alfalfa to achieve 10 tons/ac.

Are your fields producing 10 tons/ac per year of alfalfa hay?    If not, the cutting data above may give you an hint as to why.  

Many years of research here in the Palo Verde Valley, California on good producing alfalfa has shown us that good fields follow a yield trend through the season.    Our highest yielding cutting generally is the 5th cutting (May-June) at 1.61 tons/ac.   Yields diminish from there to the end of the season.

It has been our experience that if the third cutting out yields the second cutting then the field may be on it's way to 12-13 tons/ac for that year.

Responses of Alfalfa Production and Quality to Water run applications of Micro-organisms.

Below is an excerpt from Stanworth Crop Consultants Inc Research

Introduction: Questions regarding soil health in the SW deserts of the United States have been posed. Indigenous populations of micro-organisms may not be as effective in decomposition of organic matter or competitive with plant parasitic nematodes or soil borne diseases. Recent regulatory and environmental pressures have been put to growers to switch from caustic soil sterilants (methyl bromide) to alternatives. These alternatives include biological organisms as agents to help control soil borne diseases. Recently, benefits of these materials have been noted anecdotally. Increase in production and quality have been seen in treated versus untreated fields. Increase in plant analysis nutrients, primarily nitrogen and phosphorus have been observed on sugar beets. Decreases in nematode populations have been seen in treated vs untreated fields. A replicated treatment and untreated control experiment was proposed. This experiment was performed to test the efficacy of using Pure Ag Solutions micro-organisms and quantify benefits on nutrients, yields and quality of alfalfa hay.

Results: Alfalfa quality improved significantly in the treated plots. Median %ADF and %NDF decreased over 3% in treated versus untreated check plots. Energy calculations showed an increase in median Relative Feed Value from 119 to 133, TDN increased from 53.7 to 56.1. Median Crude protein increased over 1% in treated plots over the untreated check, but was not statistically significant. Yields increases were noted. Average yields of the treated plots were 1.23 tons/ac, the untreated plots averaged 1.09 tons/ac. This was not statistically significant however. Total bale counts showed there was no increase in yield, treated 1.46 tons/ac, untreated plots at 1.47 tons/ac. Bale weights were estimated at 105 lbs/bale. Comparison of soil nutrients between treatments revealed that there was no significant change in any of the soil nutrient tested in alfalfa soils treated with Pure Ag Solutions Micro-organism when compared to controls. Alfalfa plant tissue analysis of the top 6” of plants showed a similar lack of significant differences in nutrient content between treatments.

Discussion: Significant increases in alfalfa feed quality and moisture was noted in the treated over the untreated check of these fields. The mechanism of this increase is unknown. Increase in alfalfa leafiness, or higher leaf to stem ratio may be occurring in the treated areas. Possible influences from micro-organisms could be better tilthe and aeration of the soil allowing better uptake of water to the plants, giving more lush leafy growth. This experiment was performed during the peak of the desert summer. High heat stress on alfalfa causes a condition locally described as “summer slump”. Alfalfa quality and yields are depressed as plants struggle to survive through the heat. I recommend checking the same plots again in the fall as cool temperatures and un-stressed plants may respond in the treated plots.
Bibliography:

Undersander, Dan., et al. Forage Analysis Procedures. Omaha Ne.: National Forage Testing Association. July 1993

Zar, Jerrold H. Biostatistical Analysis. Englewood Cliffs N. J.: Prentice-Hall Inc. 1974

Pure Ag: http://pureagproducts.com/soil%20science/soilscience.html
Yield Estimate: http://aronquist.blogspot.com/2011/07/estimating-hay-yields-on-research.html

Below is a well written email post, it is published without permission.

Dear NIRS Consortium members, friends, and associates: It is with the deepest regret that I must tell you that Dr. John S. Shenk passed away this afternoon, Thursday, September 15 following surgery to remove a tumor on his kidney. For more than three decades, John has been an incredible driving force in the creation and advancement of NIRS technology. His unmatched passion to help everyone, everywhere benefit from NIRS brought success to scores of people and improved animal and crop production throughout the world. John accomplished this with the help, love, and unwavering support of his wife Gloria, his children, and his grandchildren. To so many of us, John's love of our Lord was exemplified in the friendships he formed with everyone he met. Several times over the last quarter century he stated that his mission in life was to simply share with others the understanding of NIRS that God had so generously shared with him. And share he did! With each sample we scan, may we bring honor to Dr. John Shenk's life's work by remembering not only what he did, but who he did it for. Information on viewing, memorial services, and related information will follow soon. Sincerely, Tim Hoerner President, The NIRS Consortium

Estimating Hay Yields on Research Trials

Estimating yields on alfalfa or other hay crops can be challenging. Hay harvesting in the desert SW United States involves a period of curing and baling on dew moisture. Raking and Baling may occur at 3 am in the morning. We like to rise early here in the hot desert, but unless one sleeps in the field, one will miss the bale count. So here is our compromise to the traditional bale count to estimate yields on large research plots. We have used this method for a variety of trials ranging from fertility to soil amendments to soil micro-organism trials (seen here).



Here is a list of items needed: A field that had been cut. A pick up truck with an arm swung out off the bed of the truck. A milk scale. A tarp. Rakes. Measuring tape. Zip lock baggies. Clipboard. Pen. And a couple of assistants.



First measure a length of windrow in replicated plot with the tape.



The length of windrow is raked onto the tarp.





The tarp is weighed, the weight is recorded on the clipboard (don't forget to post the tare weight).



A sub sample of the hay is placed into the zip lock bag. The bag is returned to the lab for dry matter test.

Yield is estimated by back calculating the net weight of the hay to tons/ac. Moisture content is then corrected by dividing the yield by the percent dry matter found from the lab analysis. Yields are commonly reported on Dry Matter or 90% dry matter basis.

Real Time Soil Moisture Reports

Recently new IT products allow traditional soil moisture meters to update to the internet to give reports in "real time".

The report to the right is an example of how soil moisture is depleted from the rootzone of an established cotton crop. Note that root depth can be estimated by the zone of water depletion in that area. For example, the 32 inch sensor began to show water just prior to the last irrigation on July 15th. We can assume that the roots are now in the vicinity of that sensor. http://www.aquaspy.com/Home.aspx