567—65.3 (455B) Requirements and recommended practices for land application of manure.
	 65.3(1) Application rate based on crop nitrogen use. A confinement feeding operation that is required to submit a manure management plan to the department under rule 65.16(455B) shall not apply manure in excess of the nitrogen use levels necessary to obtain optimum crop yields. Calculations to determine the maximum manure application rate allowed under this subrule shall be performed pursuant to rule 65.17(455B).
	 65.3(2) General requirements for application rates and practices.
	  a.   	 For confinement feeding operations required to submit a manure management plan to the department under rule 65.16(455B), application rates and practices shall be determined pursuant to rule 65.17(455B).
	  b.   	 For manure originating from an anaerobic lagoon or aerobic structure, application rates and practices shall be used to minimize groundwater or surface water pollution resulting from application, including pollution caused by runoff or other manure flow resulting from precipitation events. In determining appropriate application rates and practices, the person land-applying the manure shall consider the site conditions at the time of application including anticipated precipitation and other weather factors, field residue and tillage, site topography, the existence and depth of known or suspected tile lines in the application field, and crop and soil conditions, including a good-faith estimate of the available water holding capacity given precipitation events, the predominant soil types in the application field and planned manure application rate.
	  c.   	 Spray irrigation equipment shall be operated in a manner and with an application rate and timing that does not cause runoff of the manure onto the property adjoining the property where the spray irrigation equipment is being operated.
	  d.   	 For manure from an earthen waste slurry storage basin, earthen manure storage basin, or formed manure storage structure, restricted spray irrigation equipment shall not be used unless the manure has been diluted with surface water or groundwater to a ratio of at least 15 parts water to 1 part manure. Emergency use of spray irrigation equipment without dilution shall be allowed to minimize the impact of a release as approved by the department.
	 65.3(3) Separation distance requirements for land application of manure. Land application of manure shall be separated from objects and locations as specified in this subrule.
	  a.   	 For liquid manure from a confinement feeding operation, the required separation distance from a residence not owned by the titleholder of the land, a business, a church, a school, or a public use area is 750 feet, as specified in Iowa Code section 455B.162. The separation distance for application of manure by spray irrigation equipment shall be measured from the actual wetted perimeter and the closest point of the residence, business, church, school, or public use area.
	  b.   	 The separation distance specified in paragraph 65.3(3)“a” shall not apply if any of the following apply:
	 (1) 	 The liquid manure is injected into the soil or incorporated within the soil not later than 24 hours after the original application.
	 (2) 	 The titleholder of the land benefitting from the separation distance requirement executes a written waiver with the titleholder of the land where the manure is applied.
	 (3) 	 The liquid manure originates from a small animal feeding operation.
	 (4) 	 The liquid manure is applied by low-pressure spray irrigation equipment pursuant to paragraph 65.3(3)“d.”
	  c.   	 Separation distance for spray irrigation from property boundary line. Spray irrigation equipment shall be set up to provide for a minimum distance of 100 feet between the wetted perimeter as specified in the spray irrigation equipment manufacturer’s specifications and the boundary line of the property where the equipment is being operated. The actual wetted perimeter, as determined by wind speed and direction and other operating conditions, shall not exceed the boundary line of the property where the equipment is being operated. For property which includes a road right-of-way, railroad right-of-way or an access easement, the property boundary line shall be the boundary line of the right-of-way or easement.
	  d.   	 Distance from structures for low-pressure irrigation systems. Low-pressure irrigation systems shall have a minimum separation distance of 250 feet between the actual wetted perimeter and the closest point of a residence, a business, church, school or public use area.
	  e.   	 Variances. Variances to paragraph “c” of this subrule may be granted by the department if sufficient and proposed alternative information is provided to substantiate the need and propriety for such action. Variances may be granted on a temporary or permanent basis. The request for a variance shall be in writing and include information regarding:
	 (1) 	 The type of manure storage structure from which the manure will be applied by spray irrigation equipment.
	 (2) 	 The spray irrigation equipment to be used in the application of manure.
	 (3) 	 Other information as the department may request.
	  f.   	 Agricultural drainage wells. Manure shall not be applied by spray irrigation equipment on land located within an agricultural drainage well area.
	  g.   	 Designated areas. A person shall not apply manure on land within 200 feet from a designated area, or in the case of a high quality water resource, within 800 feet, unless one of the following applies:
	 (1) 	 The manure is land-applied by injection or incorporation on the same date as the manure was land-applied.
	 (2) 	 An area of permanent vegetation cover, including filter strips and riparian forest buffers, exists for 50 feet surrounding the designated area other than an unplugged agricultural drainage well or surface intake to an unplugged agricultural drainage well, and the area of permanent vegetation cover is not subject to manure application.
	 65.3(4) Recommended practices. Except as required by rule in this chapter, the following practices are recommended:
	  a.   	 Nitrogen application rates. To minimize the potential for leaching to groundwater or runoff to surface waters, nitrogen application from all sources, including manure, legumes, and commercial fertilizers, should not be in excess of the nitrogen use levels necessary to obtain optimum crop yields for the crop being grown.
	  b.   	 Phosphorous application rates. To minimize phosphorous movement to surface waters, manure should be applied at rates equivalent to crop uptake when soil tests indicate adequate phosphorous levels. Phosphorous application more than crop removal can be used to obtain maximum crop production when soil tests indicate very low or low phosphorous levels.
	  c.   	 Manure application on frozen or snow-covered cropland. Manure application on frozen or snow-covered cropland should be avoided where possible. If manure is spread on frozen or snow-covered cropland, application should be limited to areas on which:
	 (1) 	 Land slopes are 4 percent or less, or
	 (2) 	 Adequate erosion control practices exist. Adequate erosion control practices may include such practices as terraces, conservation tillage, cover crops, contour farming or similar practices.
	  d.   	 Manure application on cropland subject to flooding. Manure application on cropland subject to flooding more than once every ten years should be injected during application or incorporated into the soil after application. Manure should not be spread on such areas during frozen or snow-covered conditions.
	  e.   	 Manure application on land adjacent to water bodies. Unless adequate erosion controls exist on the land and manure is injected or incorporated into the soil, manure application should not be done on land areas located within 200 feet of and draining into a stream or surface intake for a tile line or other buried conduit. No manure should be spread on waterways except for the purpose of establishing seedings.
	  f.   	 Manure application on steeply sloping cropland. Manure application on tilled cropland with greater than 10 percent slopes should be limited to areas where adequate soil erosion control practices exist. Injection or soil incorporation of manure is recommended where consistent with the established soil erosion control practices.