Wednesday, October 01, 2014




Advertise with us

COUNTY AGENT REPORT

By Victoria Advocate
Dec. 20, 2010 at 6:20 a.m.


By Joe D. Janak, Jr.

Results from two local fertility demonstrations conducted in 2010 indicate soil testing pays for itself and then some. Two extensive soil tests conducted in Victoria County this past growing season indicate that soil sampling down to the depth of 12 and even 24 inches was beneficial in predicting fertilizer rates and economical yields.

Sampling at the following inch depths (0-6 inches; 6-12; 12-24; 24-36 and 36-48 inches) allowed for evaluating nutrient levels at each depth and obtaining recommendations for fertilization based on nutrients found. This was done in both grain sorghum and corn in the county with producers Chris Buzek and John Smajstrla. Fertilization recommendations were then applied accordingly at eight different levels and replicated four times within the field in small plot research. Plots were hand harvested and yields converted to acre increments.

Essentially, yield data indicated that the most economical grain sorghum crop was produced and right on target with Texas AgriLife Extension Service Soil, Water and Forage Testing Laboratory fertility recommendation for the yield goal of 5,000 pounds per acre sorghum based on a soil test taken in the 0-6 inch soil profile on that site. Recommended fertility rates were 93 pounds per acre of nitrogen, 5 pounds per acre of phosphorus and no potassium. In fact, the applications with the two closest fertility rates of nitrogen near 93 pounds were not significantly different from each other (see Table 1).

The study also shows that the Lab's recommended phosphorus rates were also on target as when more than five pounds per acre of phosphorus was applied there was not any significant difference in yield or economic return. The data also shows that grain sorghum may not effectively utilize nitrogen deeper than 12 inches in the soil.

In the corn fertility demonstration, results are similar except it's assumed the corn roots were able to utilize nitrogen from deeper soil profiles. With a yield goal of 130 bushels per acre and a recommended fertility level of 138 pounds per acre of nitrogen, 20 phosphorus and no potassium based on a soil test taken in the 0-6 inch soil profile, yield results show it too was on target. Although not significantly different, the most economical yield was obtained when less fertilizer was applied based on crediting the nitrogen found in the 0-12 inch depth. And it should be noted that when even less fertilizer was applied, according to soil nitrogen found at depths down to 24 inches and with even another 20 pounds per acre deficit, there was no significant difference in yield. This is apparently because of the deeper corn root system utilizing the nitrogen in the deeper soil profiles (see Table 2). Bushel weight in either demonstration was not affected by fertility except in the corn test were the nitrogen rate was zero. Similar to the grain sorghum demonstration, additional phosphorus above the recommended level was not beneficial to the crop.

The moral of the story and these demonstrations is to practice soil testing and consider multiple depth soil testing, 0-6 inch, 6-12 inch and even 12-24 inch depths. This data and similar data from demonstrations through Texas in 2010 will be added to the ongoing state research project for the past two years which was summarized last year this time and follows.

In 93 percent of field studies conducted in 2008 and 2009, crediting residual soil N to depths up to 24 inches produced corn yields equal to those obtained using a standard fertilizer N rate based on yield goal. Grain sorghum was slightly less consistent, but produced yields equal to a standard fertilizer N rate 70 percent of the time when soil test N was credited to depths up to 24 inches. Residual N levels ranged from 36 to 104 pounds per acre and at an average price of $0.50 per pound N, would reduce production costs by $18 to $52 per acre.

Assuming adoption of deep soil sampling methods on approximately one half of the 2.3 and 3.1 million acres of corn and grain sorghum, respectively, planted annually in Texas total savings realized by producers could exceed $48.6 million per year. (Coker, McFarland, Blumenthal).

Table 1. Evaluation of eight fertility levels on sorghum yield and profitability based on soil tests and residual soil nitrogen. Chris Buzek, Cooperator, Victoria County, 2010.

Fertilizer applied based on soil tests and laboratory recommendations (Lbs/ac) Results of grain harvest and economics 7/

Treatment Nitrogen Phosphorus Grain Yield Lbs/acre Return Above Control $/a 8/

1 (Control) 0 6/ 0 1277 d -

2 51 5/ 0 3701 c 76.68

3 71 4/ 0 4397 b 97.79

4 89 3/ 0 4721 ab 103.81

5 100 1/ 0 5042 a 112.77

6 100 1/ 12 2/ 4831 a 98.79

7 100 1/ 24 2/ 5106 a 105.66

8 100 1/ 36 2/ 5105 a 100.69

LSD for treatments 1-5 (P=.05) 5.87

LSD for treatments 5-8 (P=.05) 7.05

1/ Based on yield goal of 5000 lbs/ac sorghum and 0-6 inch soil test N credit.

2/ Phosphorus rate increased in three levels to evaluate phosphorus recommendation.

3/ Nitrogen rate based on yield goal of 5000 lbs/ac sorghum and 0-12 inch soil test N credit

4/ Nitrogen rate based on yield goal of 5000 lbs/ac sorghum and 0-24 inch soil test N credit

5/ Nitrogen rate based on yield goal of 5000 lbs/ac sorghum and 0-24 inch soil test N credit

plus 20 pounds N credit.

6/ Control plot with no nitrogen or phosphorus

7/ Means followed by same letter for treatments 1-5 or treatments 5-8 do not significantly differ

(P=.05, LSD)

8/ Based on fertilizer prices (N - $0.44/lb; and P - $0.41/lb), $5/acre for application and $4.29/cwt

sorghum price.

Table 2. Evaluation of eight fertility levels on corn yield and profitability based on soil tests and residual soil nitrogen. John Smajstrla, Cooperator, Victoria County, 2010.

Fertilizer applied based on soil tests and laboratory recommendations (Lbs/ac) Results of grain harvest and economics 7/

Treatment Nitrogen Phosphorus Grain Yield Bu/acre Return Above Control $/a 8/

1 (Control) 0 6/ 20 61 b -

2 88 5/ 20 134 a 196.15

3 108 4/ 20 135 a 191.82

4 130 3/ 20 144 a 211.78

5 140 1/ 20 142 a 201.28

6 140 1/ 40 2/ 138 a 178.11

7 140 1/ 60 2/ 139 a 174.32

8 140 1/ 0 2/ 143 a 210.51

LSD for treatments 1-5 (P=.05) 12.00

LSD for treatments 5-8 (P=.05) 13.94

1/ Based on yield goal of 130 bu/ac corn and 0-6 inch soil test N credit.

2/ Phosphorus rate dropped or doubled to evaluate phosphorus recommendation.

3/ Nitrogen rate based on yield goal of 130 bu/ac corn and 0-12 inch soil test N credit.

4/ Nitrogen rate based on yield goal of 130 bu/ac corn and 0-24 inch soil test N credit.

5/ Nitrogen rate based on yield goal of 130 bu/ac corn and 0-24 inch soil test N credit

plus 20 pounds N credit.

6/ Control plot with no nitrogen.

7/ Means followed by same letter for treatments 1-5 or treatments 5-8 do not significantly differ

(P=.05, LSD)

8/ Based on fertilizer prices (N - $0.44/lb; and P - $0.41/lb), $5/acre for application and $3.40/bu.

corn price.

Joe Janak is a Victoria County extension agent.

SHARE

Comments


THE LATEST

Powered By AdvocateDigitalMedia