Commercial Fertilizer Test on Irrigated Mountain Meadows in the Tri River Area December 2000

A. Wayne Cooley (deceased) Area Extension Agent Tri River Area CSU Extension Montrose, Colorado

Dr. Jessica Davis Associate Professor CSU Extension Ft. Collins, Colorado

Cooperators
Wolf Cattle Company Wayne Wolff, Manager Ridgway, Colorado	West Slope Ag Olathe, Colorado

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TABLE OF CONTENTS

Introduction

Objective

Materials and Methods

Results and Discussion

Summary and Conclusion

Table 1: Fertilizer Test on Mountain Meadows, Wolf Cattle Company - Dallas Creek, Ridgeway, Colorado

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Introduction

Input cost for production agriculture takes directly from the profit margin of the operation. Obviously, production agriculture requires a certain amount of input cost to produce a quality commodity that can be sold. The goal of every operation is to maximize profits.

Fertilizer is a production input that can easily increase the profit margin. However, too much fertilizer can waste money and possibly be leached or runoff to non-target sites. Too little fertilizer will result in lower yields and lost profits. How can the needed fertilizer for a given field or meadow be determined?

Soil testing is the most accurate method to date in determining what available nutrients there are for each field tested. Based on those soil test results, the amount of fertilizer required to reach a realistic yield goal for the crop being produced can be calculated.

Objective

Obtain local yield results from commercial size fertilizer plots, comparing producer's standard practices to fertilizer recommendations by CSU Extension, based on soil test analysis.

Materials and Methods

1999 Test: A test location was established at Ridgway, Colorado on the Wolf Cattle Company. The area consisted of plots that were 60 feet wide and ranged from 538 feet to 773 feet long. There were three fertilizer rates planned with each treatment replicated four times. The three fertilizer rates were 135 lbs N + 80 lbs P per acre (recommendation based on soil test analysis to reach yield goal of 4 tons/A); 135 lbs/A N; and 80 lbs/A N (standard practice of the producer).

The fertilizer utilized in the test for the nitrogen source was ammonium nitrate (34-0-0) and the phosphorus source was monoammonium phosphate (11-52-0). The fertilizer was applied on April 27, 1999 by West Slope Ag, utilizing their commercial applicator trucks. The area had been pre-irrigated and rainfall followed for several days following the fertilizer application.

The plots were harvested and baled in small rectangular bales on July 1, 1999. The area used for yield measurements was 35 feet by 370 feet. The small bales were weighed at random in each plot and then the total number of bales counted to determine yield. Plot weights were converted to pounds per acre.

2000 Test: The test was repeated during the 2000 season using the same location and plots. However, soil samples were taken again (by treatment) to determine the amount of fertilizer needed to reach the same yield goal as 1999, based on CSU Extension recommendations. The three fertilizer rates were 110 lbs N + 80 lbs P per acre (recommendation based on soil test analysis); 110 lbs/A N; and 80 lbs/A N (standard practice of producer).

The fertilizer source utilized in the test was the same as the 1999 test. The fertilizer was applied on April 27, 2000 by West Slope Ag, utilizing their commercial applicator trucks. Irrigation was started on May 8, 2000. Rainfall from April 27, 2000 to May 8, 2000 totaled 1.3 inches and no more rain was received until July 8, 2000. This was a light rain following the hay being cut on July 6, 2000.

The plots were harvested and baled in small rectangular bales. The hay was weighed and stacked on July 12, 2000. The area used for yield measurements was 35 feet by 429 feet. All bales were picked up by the stack wagon in each plot and weighed on commercial weigh pads. Plot weights were converted to pounds per acre.

Results and Discussion

1999 Test: There was no statistical differences in yields among the fertilizer treatments (Table I). However, the nitrogen plus phosphorus treatment tended to yield higher than either rate of nitrogen alone. The nitrogen plus phosphorus rates were what was required according to the soil test analysis and CSU's recommendations.

In addition, the yield calculations in 1999 were randomly weighing a few bales per plot, counting the bales per plot, and then converting to pounds per acre. This may not have been an accurate enough measurement since there was only a little more than a quarter of an acre per plot harvested to measure yields. In the 2000 test, all bales per plot were weighed and the area to measure yields was slightly over one third acre per plot.

2000 Test: The nitrogen plus phosphorus treatment was statistically significant in producing a higher yield than either rate of nitrogen alone (Table I). This significant difference in yields also provided an additional $30 per acre profit by soil testing and utilizing CSU's fertilizer recommendations over the next best treatment.

Summary and Conclusions

Soil testing each year provides a means for determining the nutrient requirement for a given field. Although the same plot area was used in 1999 and 2000, the fertilizer requirements (based on soil testing) were slightly different to obtain the same yield goals. Without soil sampling each year, there would have been no way to know that different fertilizer amounts should be applied to obtain similar yield results.

The trend in the1999 test and the significant increase in yield in the 2000 test, strongly supports the benefits of soil testing. Also, the CSU fertilizer recommendations (based on soil test analysis) for grass hay and pastures appear to be reasonably accurate.

Table 1: Fertilizer Test on Mountain Meadows, Wolf Cattle Company - Dallas Creek, Ridgway, Colorado

1999 Test
Treatment	Yield (lbs/A)	Hay Value ($/A) __1/	Fertilizer Cost ($/A)	Return ($/A) __2/
80 lbs/A Nitrogen (N)	4363 A _3/	218.15	24.70	193.45
135 lbs/A N	4771 A	238.55	41.69	196.86
135 lbs/A N + 80 lbs/A Phosphorus (P)	5279 A	263.95	62.98	200.97
_1/ Hay price calculated @ $100/ton _2/ Return = Hay value minue fertilizer cost _3/ Treatments with the same letter are not significantly different (P<0.05) by analysis of variance.
2000 Test
Treatment	Yield (lb/A)	Hay Value ($/A) __4/	Fertilizer Cost ($/A)	Return ($/A) __5/
80 lbs/A N	4549 B _6/	193.33	23.50	169.83
110 lbs/A N	4898 B	208.16	32.40	175.76
110 lbs/A N + 80 lbs/A P	5966	253.55	48.19	205.36
_4/ Hay price calculated @ $85/ton _5/ Return = Hay value minue fertilizer cost _6/ Treatments with the same letter are not significantly different (P<0.05) by analysis of variance.

Colorado State University, U.S. Department of Agriculture and Delta, Mesa, Montrose & Ouray Counties cooperating. Extension programs are available to all without discrimination. No endorsement of products is intended nor is criticism of products mentioned.