EQ392, New April 2003

Determine the value of the three types of manure for a corn-soybean rotation with the following soil test recommendations: For 150 bushels per acre corn: 195 pounds N, zero P_{2}O_{5} and 60 pounds K_{2}O. For 40 bushels per acre soybeans: zero N, zero P_{2}O_{5} and 75 pounds K_{2}O (soil test results were 116 [very high] for phosphorus, 280 for potassium, and 2.9 for organic matter).

The last crop was soybeans, so we can take credit for 30 pounds N from the soybeans and apply 165 pounds of N for corn.

Using all the slurry manure from 150 head (Table 20), the available N is 3,420 + 6,045 = 9,465 pounds of N; the available P_{2}O_{5} is 8,250 pounds x 0.95 = 7,838 pounds; and the available K_{2}O is 11,850 pounds x 0.95 = 11,258 pounds. With 9,465 pounds of available N, we can apply 165 pounds of N to 57 acres. Using all the manure will also apply 8,250 pounds of P_{2}O_{5} and 11,850 pounds of K_{2}O (Table 20). For the 57 acres of corn, the soil test calls for zero P_{2}O_{5} and 3,420 pounds K_{2}O. No return should be expected from the 8,250 pounds of P_{2}O_{5} . To have 3,420 pounds of K_{2}O available, we must apply 3,600 pounds at 0.95 percent availability. Adding the value of 9,465 pounds of N at $0.30 per pounds = $2,840 to the value of 3,420 pounds of K_{2}O at $0.15 per pounds = $513, the total value is $3,353. If all the P_{2}O_{5} and K_{2}O applied had been needed, the value would have been $6,096 (Table 20).

For soybeans and applying the solid manure at a rate to supply 75 pounds of K_{2}O per acre, the 11,258 pounds of available K_{2}O will fertilize 11,258/75 = 150 acres of soybeans. Since the soil test did not call for any N or P_{2}O_{5} , the only value to be credited to the manure is for 11,258 pounds of available K_{2}O at $0.15 = $1,689 (Table 20).

**Caution**

Since the soil test P is very high, any addition of manure increases the risk of downstream pollution from phosphorous and may not be allowed under developing regulations.

**Table for example 1**

Value of manure nutrients used by 150 bushels per acre corn (based on soil test)

Herd size (1,000-pound animals) | |||
---|---|---|---|

150 | 300 | 600 | |

Gross value of excreted manure | $12,542 | $25,084 | $50,168 |

Value of lagoon N at 165 pounds per acre |
$732 | $1,463 | $2,927 |

Application acres | 15.0 | 30.0 | 59.0 |

Value of P_{2}O_{5} used by corn |
0 | 0 | 0 |

Value of K_{2}O used by corn |
$135 | $270 | $531 |

Value of lagoon nutrients used | $867 | $1,733 | $3,458 |

Value of slurry N at 165 pounds per acre | $2,840 | $5,679 | $11,358 |

Application acres | 57 | 115 | 229 |

Value of P_{2}O_{5} used by corn |
0 | 0 | 0 |

Value of K_{2}O used by corn |
$513 | $1,035 | $2,061 |

Value of slurry nutrients used | $3,353 | $6,714 | $13,419 |

Value of solid N at 165 pounds per acre | $1,210 | $2,318 | $4,636 |

Application acres | 24 | 49 | 98 |

Value of P_{2}O_{5} used by corn |
0 | 0 | 0 |

Value of K_{2}O used by corn |
$216 | $441 | $882 |

Value of solid nutrients used | $1,426 | $2,759 | $5,518 |

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