United States Department of Agriculture
Natural Resources Conservation Service

Wyoming

Teton Mountain RangeGo to Accessibility Information
Skip to Page Content

Section 6 - Land Base Requirement

In this section you will estimate the amount of crop land necessary to recycle the manure your animals produce in a year (calculated in Section 4).

You will need to know the crop(s) that will be grown on the land and your yield goal for those crops. You'll need an analysis of your livestock manure; if you have none, download or read on-line the table, Nutrient Content of Solid Manure in Wyoming, based on analyses of manure from Colorado livestock. You will also need to download or view on-line our table, Nutrient Content of the Harvested Part of Selected Wyoming Crops, which provides dry matter content, typical yields, and nutrient contents of a number of crops grown in Wyoming.

Preliminary data

To determine how much land is required to utilize all of the manure produced by a confined feeding operation over the long-term, you need the following information:

1. What crop (or crops) will receive the manure?

2. What is the yield goal for each crop (based on average yield for the last five years plus 5%)?

3. What is the percent dry matter of the harvested portion of each crop (silage crops only)? (See Nutrient Content of the Harvested Part of Selected Wyoming Crops table.)

4. What are the plant nitrogen and phosphorus percentages of each crop? (See Nutrient Content of the Harvested Part of Selected Wyoming Crops table.)
 

5. What are the total nitrogen and phosphorus contents (lb./ton) of the manure, as-is? (See your manure analysis, if you have one, or the Nutrient Content of Solid Manure in Wyoming table.)

6. Which will you use, N or P, to calculate your land base?

7. How much manure does your operation produce per year (from Section 4)?
 
 

Calculating Land Base Requirement

Example 1. N-based; Example 2. P-based; Example 3. N-based, two crops

Step 1. Calculate nutrient removal

A. Convert yield per acre to pounds per acre
  • For silage, tons/A x % dry weight x 2,000 lb./Ton = lb/acre
  • For grain and oil crops, bu/A x lb/bu x 2,000 lb/ton = lb/acre
  • For other crops, tons/A x 2,000 lb/ton = lb/acrE

B. Convert pounds per acre to pounds N per acre

lb/acre x % N content = lb N/acre

Step 2. Calculate manure application rate

Divide N removal (from Step 1) by the N content of your manure (from manure analysis or table).

lb N removal/acre ÷ lb N/ton manure = tons manure/acre

Step 3. Calculate land base requirement

Divide your total manure production per year by the manure application rate (from Step 2).

tons manure/year ÷ tons manure/acre = acres required

Example 1. Land Base Requirement based on N

Step 1. Calculate nitrogen removal

a. Convert crop yield to dry matter yield.
b. Convert dry matter yield from tons or bushels to pounds.
c. Convert pounds of dry matter to pounds of nitrogen.

Crop = corn silage
Yield goal = 35 tons/acre
From Table 1, we find that corn silage is 35% dry matter and the dry matter is 1.1% N.

Therefore,

35 tons silage/acre x 0.35 = 12.25 tons dry matter/acre

12.25 tons dry matter/acre x 2000 lb/ton = 24,500 lb dry matter/acre

24,500 lb dry matter/acre x 0.011 = 270 lb N/acre

Step 2. Calculate manure application rate

Using the nitrogen content of your manure, calculate how much manure is required to supply the amount of nitrogen removed by the crop (determined in Step 1).

According to Table 2, the manure from Frank's Feedlot has 23 lb N/ton. If manure is applied every year, we assume 100% N availability.

270 lb N/acre ÷ 23 lb N/ton = 12 tons manure/acre

Step 3. Calculate land base requirement

Using the manure application rate from Step 2, calculate how many acres are required to dispose of your annual production of manure.

Frank's Feedlot produces 3375 tons manure/year.

3375 tons/year ÷ 12 tons/acre = 281 acres required

Example 2. Land Base Requirement based on P

Step 1. Calculate phosphorus removal

a. Convert crop yield to dry matter yield.
b. Convert dry matter yield from tons or bushels to pounds.
c. Convert pounds of dry matter to pounds of phosphorus.

Crop = corn silage
Yield goal = 35 tons/acre
From Table 1, we find that corn silage is 35% dry matter and the dry matter is 0.25% P.

Therefore,

35 tons silage/acre x 0.35 = 12.25 tons dry matter/acre

12.25 tons dry matter/acre x 2000 lb/ton = 24,500 lb dry matter/acre

24,500 lb dry matter/acre x 0.0025 = 61 lb P/acre

Step 2. Calculate manure application rate

Using the phosphorus content of your manure, calculate how much manure is required to supply the amount of phosphorus removed by the crop (determined in Step 1).

According to Table 2, the manure from Frank's Feedlot has 10 lb P/ton. If manure is applied every year, we assume 100% P availability.

61 lb P/acre ÷ 10 lb N/ton = 6 tons manure/acre

Step 3. Calculate land base requirement

Using the manure application rate from Step 2, calculate how many acres are required to dispose of your annual production of manure.

Frank's Feedlot produces 3375 tons manure/year.

3375 tons/year ÷ 6 tons/acre = 562 acres required

Example 3. Land Base Requirement, based on N #2

Step 1. Calculate nitrogen removal

a. Convert crop yield to dry matter yield.
b. Convert dry matter yield from tons or bushels to pounds.
c. Convert pounds of dry matter to pounds of nitrogen.

Crop = irrigated barley
Yield goal = 80 bushels / acre
From Table 1, we find that barley grain weighs 48 lb/bu and the grain is 1.8% N. Similarly, the 80 bushel crop produces about 2 tons of straw with a nitrogen content of 0.8%.

Therefore,

80 bu/acre x 48 lb/bu = 3,840 lb/acre

3,840 lb/acre x 1.8% N = 69 lbs N / acre

2 tons/acre straw x 0.8% N x 2,000 lbs/ton = 32 lbs N / acre

Total = 101 lbs N/acre

Step 2. Calculate manure application rate

Using the nitrogen content of your manure, calculate how much manure is required to supply the amount of nitrogen removed by the crop (determined in Step 1).

According to Table 2, the manure from Frank's Feedlot has 23 lb N/ton. If manure is applied every year, we assume 100% N availability.

101 lb N/acre ÷ 23 lb N/ton = 4.4 tons manure/acre

Step 3. Calculate land base requirement

Using the manure application rate from Step 2, calculate how many acres are required to dispose of your annual production of manure.

Frank's Feedlot produces 3375 tons manure/year.

3375 tons/year ÷ 4.4 tons/acre = 767 acres required

Example 4. Land Base Requirement, based on N, with two different crops

Frank's Feedlot decides to spread half the manure on sorghum silage and half the manure on corn silage.

Step 1a. Calculate nitrogen removal for first crop

Crop = corn silage
Yield goal = 35 tons/acre

From Table 1, we find that corn silage is 35% dry matter and the dry matter is 1.1% N.

Therefore,

35 tons silage/acre x 0.35 = 12.25 tons dry matter/acre

12.25 tons dry matter/acre x 2000 lb/ton = 24,500 lb dry matter/acre

24,500 lb dry matter/acre x 0.011 = 270 lb N/acre

 

Step 1b. Calculate nitrogen removal for second crop

Crop = sorghum silage
Yield goal = 30 tons/acre

From Table 1, we find that sorghum silage is 30% dry matter and the dry matter is 1.4% N.

Therefore,

30 tons silage/acre x 0.30 = 9 tons dry matter/acre

9 tons dry matter/acre x 2000 lb/ton = 18,000 lb dry matter/acre

18,000 lb dry matter/acre x 0.014 = 252 lb N/acre

 

Step 1c. Calculate average nitrogen removal for all crops

(270 lb N removed /acre corn silage + 252 lb N removed/acre sorghum silage)
2

= 261 lb N removal/acre average

Step 2. Calculate manure application rate

Using the nitrogen content of your manure, calculate how much manure is required to supply the amount of nitrogen removed by the crop (determined in Step 1c).

According to Table 2, the manure from Frank's Feedlot has 23 lb N/ton. If manure is applied every year, we assume 100% N availability.

261 lb N/acre ÷ 23 lb N/ton = 11 tons manure/acre

Step 3. Calculate land base requirement

Using the manure application rate from Step 2, calculate how many acres are required to dispose of your annual production of manure.

Frank's Feedlot produces 3375 tons manure/year.

3375 tons/year ÷ 11 tons/acre = 307 acres required

Table 1. Nutrient Content of the Harvested Part of Selected Wyoming crops

Nutrient Content of the Harvested Part of Selected Wyoming crops
Crop Dry
weight		 Typical
yield*		 N content in
harvested material		 P content in
harvested material
lb/bu
unit/A
------------------ % ------------------
(harvest dry weight basis**)
Grain crops
Barley
48
80 bu.
1.8
0.34
 
2 tons straw
0.8
0.11
Corn
56
165 bu.
1.6
0.28
3.5 tons stover
1.1
0.20
Oats
32
60 bu.
2.0
0.34
 
1.5 tons straw
0.6
0.16
Rye
56
30 bu.
2.1
0.26
1.5 tons straw
0.5
0.12
Sorghum (dryland)
56
60 bu.
1.7
0.36
 
3 tons stover
1.1
0.15
Wheat (dryland)
60
40 bu.
2.1
0.62
1.5 tons straw
0.7
0.07
Oil crops
Canola
50
35 bu.
3.6
0.79
 
3 tons straw
4.5
0.43
Soybeans
60
35 bu.
6.3
0.64
2 tons stover
1.5
0.22
Sunflower (dryland)
25
1,100 lb.
3.6
1.71
 
2 tons stover
1.5
0.18
Forage crops
Alfalfa
4 tons
2.3
0.22
Big bluestem
3 tons
1.0
0.85
Birdsfoot trefoil
3 tons
2.5
0.22
Bromegrass
3 tons
1.9
0.21
Alfalfa-grass
4 tons
1.5
0.27
Little bluestem
3 tons
1.1
0.85
Orchardgrass
4 tons
1.5
0.20
Red clover
3 tons
2.0
0.22
Reed canarygrass
4 tons
1.4
0.18
Ryegrass
4 tons
1.7
0.27
Switchgrass
3 tons
1.2
0.10
Tall fescue
4 tons
2.0
0.20
Timothy
3 tons
1.2
0.22
Wheatgrass (dryland)
1 ton
1.4
0.27
         
Crop
Dry
Wt. 
Typical
yield* 
N content in
harvested material
P content in
harvested material
 
%
tons/A
--------------- % ---------------
(harvest dry weight basis)**
Silage crops
Alfalfa haylage
50
10 wet / 5 dry
2.8
0.33
Corn silage
35
20 wet / 7 dry
1.1
0.25
Forage sorghum
30
20 wet / 6 dry
1.4
0.19
Oat haylage
40
10 wet / 4 dry
1.6
0.28
Sorghum-sudan
50
10 wet / 5 dry
1.4
0.16
Sugar crops
Sugar beets
20
0.2
0.03
Turfgrass
Bluegrass
2
2.9
0.43
Bentgrass
2
3.1
0.41
Vegetable crops
Bell peppers
9
0.4
0.12
Beans, dry
1
3.1
0.45
Cabbage
20
0.3
0.04
Carrots
13
0.2
0.04
Celery
27
0.2
0.09
Cucumbers
10
0.2
0.09
Lettuce, (heads)
14
0.2
0.08
Onions
18
0.3
0.06
Peas
2
3.7
0.40
Potatoes
14
0.3
0.06
Snap beans
3
0.9
0.26
Sweet corn
6
0.9
0.24

Adapted from the USDA Agricultural Waste Management Field Handbook.
*Typical yields are for irrigated production unless noted otherwise.
**Nutrient Contents are on a harvest dried basis and do not need to be corrected for content except for silage and haylage

Table 2. Nutrient Content of Solid Manures in Wyoming
(based on 1996 survey from Colorado State University)

Nutrient Content of Solid Manures in Wyoming (lb/ton - fresh weight.)

Manure Source

Nitrogen

Phosphorus
Beef

23

10
Dairy

13

7
Sheep

29

11
Horse

19

6
Chicken

30

28
Llama

31

12
Turkey compost

38

35
Dairy compost

16

8

CNMP Workbook | Table of Contents