J. Dairy Sci. 84:966–973
American Dairy Science Association, 2001.
A Survey of Dairy Farming in Pennsylvania:
Nutrient Management Practices and Implications
Z. Dou,* D. T. Galligan, C. F. Ramberg, Jr.,
C. Meadows, and J. D. Ferguson
University of Pennsylvania
School of Veterinary Medicine
Center for Animal Health and Productivity
382 West Street Road, Kennett Square, PA 19348
A survey was conducted to collect information on Animal agriculture contributes signiﬁcantly to non-
nutrient management practices on dairy farms in point source nutrient pollution of ground and surface
south-central Pennsylvania. Of the 994 responding waters. Evidence linking intensive animal farming
farms, the average farm consisted of 64 lactating cows, and off-farm transport of excess nutrients with water
10 dry cows, 41 heifers, and 17 calves with 69.7 ha of quality problems is plentiful. In southeastern Pennsyl-
tillable land. Manure from lactating cows was mainly vania, an area of intensive animal and cash crop farm-
collected on a daily basis (84% of the farms) and stored ing, nitrate concentrations exceeded the EPA drinking
as slurry or liquid (73%), while dry cow and heifer water standard of 10 mg of nitrate-N/L in more than
manure was collected weekly or less frequently (69 50% of the private wells surveyed (Swistock et al.,
and 85% of the farms) and stored as solid stack or 1993). In Sussex County, Delaware, a maximum of 72
bedded pack (67 and 82%). Manure utilization fea- and mean of 10 mg of nitrate-N/L was found in 231
tured consistent use of on-farm spreading, with limited wells in areas of intensive poultry operations, com-
incorporation, to corn or small grain ﬁelds before pared with a maximum of 18 and mean of 6 mg/L in
planting. Spreading on perennial forages or pasture 202 wells in other areas (Andres, 1995). Duda and
was also common. Irrigation or injection of manure Finan (1983) showed that the greatest potential for
occurred on less than 5% of the farms. Only 20% of accelerated eutrophication occurs in watersheds with
the farms reported manure nutrient testing, con- intensive animal production.
trasting to over 90% for soil testing. Farm advisors Various programs have been developed to help pro-
and their services can be of vital importance in helping ducers manage the vast amount of manure nutrients
producers make conscientious management decisions in an agronomically sound and environmentally ac-
for enhanced nutrient utilization. For example, ration ceptable manner. Yet, in spite of a long-term intensive
balancing involved the services of feed and mineral effort, animal agriculture still faces the challenge of
sales representatives (85% of the farms), independent balancing nutrients for animals, crops, and on the
consultants (12%), and veterinarians (5%). Manure whole farm with environmental responsibility. This is
nutrient crediting to determine manure application particularly true for phosphorus (P) because of wide-
rates was made by fertilizer dealers (40%), crop advi- spread soil P buildup and the associated enrichment
sors and independent consultants (31%), and others. of P in runoff loss in areas with intensive animal opera-
Nutrient management strategies and efforts must ad- tions (Sims, 2000). More recently, mounting public
dress the speciﬁc needs of farms with different animal concerns and real as well as perceived potential im-
densities and nutrient balances in order to be effective pacts on water quality from continuous animal farm-
and applicable on the majority of farms. ing have prompted regulatory actions to be taken, ﬁrst
(Key words: dairy farm, nutrient management, by several states and lately by federal agencies, to
survey) guide animal waste handling and utilization strategies
through both mandatory and voluntary measures.
Abbreviation key: AEU = animal equivalent unit. Pennsylvania was the ﬁrst state in the nation that
enacted a nutrient management law (Act 6, 1993) and
established nutrient management regulations. Ac-
cordingly, any operations with animal density ex-
Received September 18, 2000.
Accepted December 6, 2000. ceeding 2240 kg of live animal weight per hectare on
Corresponding author: Z. Dou; e-mail: firstname.lastname@example.org. an annual basis are required to develop and implement
OUR INDUSTRY TODAY 967
nutrient management plans (Beegle et al., 1997). The
animal density criterion (2240 kg of live animal weight
per hectare) is equivalent to two animal equivalent
units (AEU) per acre; an AEU is deﬁned as 1000 lb of
live weight. Farms with less than two AEU per acre
are encouraged to voluntarily develop nutrient man-
agement plans. Dairy farming, the number one ag-
ricultural industry in Pennsylvania with total milk
production ranking fourth in the nation, must comply
with the regulations.
Farms differ greatly in terms of resources and their
allocations, management skills, and preferences. Nu-
trient dynamics and balances on individual farms are
determined by many factors associated with the char-
acteristics of farm resources and management choices.
Collecting benchmark information and identifying
current management patterns and practices is an im-
portant step in assessing how current practices affect Figure 1. A dairy farming survey was conducted in nine counties
in south-central Pennsylvania (as highlighted). Eight of the nine
farm productivity and nutrient ﬂows. Such informa- counties are located in the Chesapeake Bay watershed (the shaded
tion is essential for directing research and educational area).
efforts to develop management techniques for im-
proved nutrient utilization efﬁciency and water
quality. mailing of the same questionnaire was sent to those
We conducted a survey of dairy farming in south- who had not responded. There were 994 valid returns,
central Pennsylvania to identify farm characteristics equivalent of 25% of the initial targets. Nearly half of
and practices and to explore factors and management the respondents expressed interest in survey results,
choices that are associated with farm productivity and and the survey summary was subsequently sent to
nutrient balance status. The present paper reports those who requested it.
results and discusses the implications related to nutri- The questionnaire consisted of 48 queries, a mix of
ent management practices and relevant issues. Other open- and closed-ended questions with multiple
data involving farm productivity and associated fac- choices when applicable. The questions sought infor-
tors will be presented separately. mation on relevant management practices as well as
farm attributes involving animal numbers and feeding
MATERIALS AND METHODS (25 questions), manure handling and cropping (21
questions), plus farm labor information (two ques-
The survey targeted nine counties in south-central tions). Questions on herds and cropping were oriented
Pennsylvania (Figure 1). These counties are in the toward farm characteristics in general (e.g., herd de-
Susquehanna River basin, which is a major tributary mographics, crop acreage), while questions on feeding
of the Chesapeake Bay. The number of lactating cows and manure were reﬂective of management choices
in the nine counties (240,000 head) accounted for 37% and practices (e.g., number of groups for feeding and
and milk production accounted for 41% of the state manure collection method and frequency).
totals (Anonymous, 1997). Some participants chose not to respond to every
In September 1996, introduction letters were sent question in the survey; hence the percentage, wher-
to all dairy operations in the designated area (a total of ever it was used, was the percentage response to the
3790 farms), announcing that a survey questionnaire individual question. Also, some questions allowed mul-
would soon arrive and stating that the main interest tiple answers and thus data might not total 100%.
of the survey was to identify systemic approaches for
improved nutrient utilization and farm productivity.
RESULTS AND DISCUSSION
The questionnaires were sent out within 2 wk with
preaddressed and prestamped return envelopes. We The average herd consisted of 64 lactating cows, 10
also offered the recipients an opportunity to receive dry cows, 41 heifers, and 17 calves with a milk yield
survey results while maintaining their conﬁdentiality. of 27 kg/d (60 lb/d per cow). Holstein as the main breed
Nearly 600 returns had been received by the end of was reported by 97% of the farms; other breeds were
December, 1996. At the beginning of 1997, a second present on no more than a dozen farms. It is worth
Journal of Dairy Science Vol. 84, No. 4, 2001
968 DOU, ET AL.
noting that a number of farms also raised other food affects the quantity of bedding or dilution water used
animals in addition to dairy cows, including poultry in a manure handling system, which in turn, inﬂu-
(122 farms), beef/steer (135 farms), and pigs (67 ences the manure characteristics and selection of col-
farms), although no question was asked about the lection, transfer, storage, and transport options (EPA,
number of nondairy animals present. 1998). On the surveyed farms in the present study,
The average tillable area was 69.7 ha, with the most lactating cows were mainly housed in free-stall (35%)
common crops being corn for grain (22.8 ha), corn for or stanchion/tie-stall facilities (68% of the respon-
silage (16.8 ha), and alfalfa (16.4 ha). Most farms grew dents), while dry cows and heifers were mostly on bed-
their own forages for the cows; 59% reported no pur- ded pack (61 and 74%) or pasture (57 and 64%).
chase of forages, while 18% sold forages. Grain pur- Other collection methods for lactating cow manure
chases were reported by 70% of the respondents, while included gravity ﬂow (94 farms), slotted ﬂoor (26
30% also reported selling grains. On average, there farms), and ﬂushing (15 farms). The lack of extensive
were fewer than two full-time workers plus one or two use of ﬂushing systems on these Pennsylvania dairies
part-timers per farm. Clearly, most of the surveyed
was perhaps due to the relatively small scale of the
dairies were primarily family-based operations grow-
operations. Flushing systems have a primary advan-
ing forages and grains on site to meet cow re-
tage of being automated and thus can be labor efﬁcient.
However, they are mainly favored by large operations,
perhaps due to the cost of installation and operation.
Manure Handling Before Field Spreading In California, 77% of dairies in a survey used ﬂushing
Manure handling differed considerably between lac- systems to collect manure; those dairies averaged 837
tating cows and dry cows and heifers on most farms lactating cows (Meyer et al., 1997). Nationwide esti-
in terms of collection method, frequency, and storage mates of prevalence of ﬂushing systems on dairy farms
form (Table 1). Lactating cow manure was collected were: 0.2% on farms of <100 head, 4% on farms of
more frequently (daily or every 2 to 3 d by 84% of 100 to 199 head, and 27% for 200 head or greater
the farms) and stored mostly in the form of slurry to (APHIS, 1996).
semisolid or liquid (73% of the farms). Dry cow and Although no speciﬁc questions were asked about the
heifer manure was collected on a weekly or less fre- duration or capacity of manure storage, it appeared
quent basis (69 and 85%) and stored mainly as solid that the majority stored manure for a few months be-
or bedded pack (67 and 82%). Often, type of housing cause most farms reported manure spreading in all
four seasons: 99% reported applications in spring and
summer, 64% in fall, and 75% in winter. Besides the
Table 1. Manure handling practices before ﬁeld application on Penn-
sylvania dairy farms. conventional manure handling and storage practices,
use of alternative methods was uncommon: only two
farms reported using a methane fermenter, and six
Manure handling Milk cow Dry cow Heifer farms used aerobic or anaerobic treatment lagoons.
% 1 Nearly 30% of the farms reported no storage for
Collection method (944)2 (932) (920) lactating cow manure, which was instead either depos-
Scrape (gutter/alley) 84 34 22 ited directly on pasture or hauled and spread to ﬁelds
Bedded pack 10 67 82
Slotted ﬂoor 3 1 4 on a daily basis. Manure storage is generally believed
Water ﬂush 2 0.3 0.2 to improve nutrient management and thus is favored
Gravity ﬂow 10 1 0.7 by public manure management programs (Nowak et
Collection frequency (915) (868) (867) al., 1998). Yet, the potential beneﬁts associated with
Daily or every few days 84 29 12
Weekly or every few weeks 6 38 42 having storage structures on site (e.g., conservation of
Monthly or longer 3 31 43 nutrients, ﬂexibility of haul and spreading, opportu-
Storage form (937) (898) (883) nity for testing nutrients for accurate applications)
No storage (pasture or daily spread) 30 21 16
Solid/pack 9 67 82 may not be realized for the purpose of protecting wa-
Slurry/semisolid 32 14 13 ters unless concomitant efforts are made in all aspects
Liquid 41 12 8
of manure handling and utilization. For instance, ex-
Reported as percentage of the response to each question; data cessive nutrient applications and elevated environ-
do not total 100% due to more than one choice checked by some
mental losses could still occur if stored manure is
Number shown in parentheses is the number of responses to that spread on ﬁelds without careful timing and proper
speciﬁc question. nutrient crediting.
Journal of Dairy Science Vol. 84, No. 4, 2001
OUR INDUSTRY TODAY 969
Table 2. Manure application practices on Pennsylvania dairy farms: application during nongrowing season) might also fa-
application frequency and timing of incorporation.
vor runoff loss of P. Phosphorus concentrations in ani-
Manure type (%)1 mal manure typically are many times greater than in
Application practice Solid Semisolid Liquid soils. Moreover, recent studies found that 50 to 70%
of total P in various manures was water extractable
Spreading frequency (686) (382) (486)
Daily haul and spread 3 11 2 (Dou et al., 2000a, 2000b). With manure containing a
Weekly 9 20 4 high concentration of total P and a large proportion of
Monthly 37 27 17 water soluble P applied and left on the soil surface,
4 times per year 28 20 27
3 times per year 11 11 24 rainwater interacts with the manure, dissolving and
2 times per year 11 9 21 extracting P. The dissolved P can be either leached
Once a year 2 1 2 into the underlying soil, contributing to the pool of
Timing of incorporation (625) (386) (482) plant available soil P or, if rainfall exceeds the inﬁl-
No incorporation 23 23 18
7 d or more after 56 41 22 tration rate and slope and soil characteristics are fa-
Within 5–6 d 5 8 5 vorable, it can be transported in surface runoff. Ma-
Within 2–4 d 11 14 31 nure treatments to “stabilize” the most vulnerable P
Within 1 d 4 10 17
Same day 1 4 7 fraction prior to ﬁeld spreading are clearly desirable.
For instance, amending manure with alum or coal com-
Reported as percentage of the response to each question; data
do not total 100% due to more than one choice checked by some
bustion power plant ﬂy ash materials reduced the wa-
producers. ter-soluble fraction of P in manure (Moore et al., 2000;
Number shown in parentheses is the number of responses to that Toth et al., 2000).
Other Relevant Issues
Manure Utilization and Field Spreading
Nutrient testing and record keeping. When
Manure was largely utilized on the same farm where asked about manure testing for nutrients, 77% of the
it was generated. Only 98 farms (10%) reported selling respondents checked “None”; about 20% reported test-
or giving away manure, which included 10 out of the ing of total N, P, and K; a small number of farms
19 farms in the high animal density category (i.e. > 2 also tested for ammonia-N. Record keeping of ﬁelds
AEU/ac). Meanwhile, 115 farms reported receiving or receiving manure was reported by less than 35% of
importing manure, of which none were in the high the farms. An interesting contrast was that 75% of the
animal density category. For on-farm use, manure was farms reported soil nutrient testing every 1 to 3 yr
applied to ﬁelds of corn or small grains before planting with an additional 20% every four or more years; only
on almost all farms (99%). Manure spreading on other about 4% of the farms “Never” had soil tested for nutri-
crops was also common: on legume and alfalfa by 343 ents. Moreover, 81% kept their soil test records. The
farms, grass by 356 farms, cover crop by 517 farms, and absence of manure nutrient testing appeared to be
pasture by 285 farms. Most applications were made widespread rather than local. A North Carolina survey
by surface spreading; alternative methods (spray and reported manure testing by 37% of the dairy farms
irrigation or injection) were reported by fewer than compared with soil testing by 86% of the farms (Hoban
5% of the respondents. and Clifford, 1995). A California study reported that no
Incorporating manure in a timely fashion to con- producers tested manure for nutrients and few tested
serve the ammonia-N for crop utilization and prevent soils on any regular basis (Meyer et al., 1997). Nation-
volatilization loss was not practiced by many farms. wide, manure testing was estimated to be only 14%
Depending on the forms of manure (solid, semisolid, on dairy operations (EPA, 1998).
or liquid), incorporation within 1 d of spreading was Farmers generally understand the nutrient values
reported by 5 to 24% of the farms, while no incorpora- and other beneﬁcial effects of manure application on
tion or incorporation after 7 d of spreading occurred soils. Yet, being able to recognize these values does
on 40 to 78% of the farms (Table 2). Meisinger and not necessarily mean that the nutrients are taken into
Jokela (2000) estimated ammonia volatilization loss account properly when manure is land applied. An
from spring-applied dairy manure to be 35% of the extensive Wisconsin study of 1179 dairy and beef oper-
ammonia-N in the ﬁrst day, and 100% if no incorpo- ations concluded that, although farmers recognized
ration. the nutrient value of manure, few were attempting to
In addition to the high potential of ammonia volatil- credit manure nutrients; and fewer still were doing so
ization loss, the prevalent ﬁeld practices on these in an accurate fashion (Nowak et al., 1998). Of those
farms (surface spreading, limited or no incorporation, farms, 30% tried to credit manure N, of which merely
Journal of Dairy Science Vol. 84, No. 4, 2001
970 DOU, ET AL.
6% did so accurately, while 66% underestimated and be reﬂected by the survey results of who balanced the
28% overestimated manure N by 11% or more com- rations for animals and who determined fertilizer and
pared with the local guidelines. In sum, fewer than manure application rates on the surveyed farms.
2% of all survey participants spreading manure on On most of the farms, ration formulation for dairy
corn ground were crediting manure N with any degree cows was made by representatives of feed suppliers
of accuracy (Nowak et al., 1998). (66% of the farms) or mineral dealers (19%). Others
Some farmers and their advisors might have cred- providing ration formulation service included indepen-
ited manure nutrients by using standard book values dent consultants (12%), veterinarians (5%), and pro-
in the absence of manure testing. Although a better ducers themselves (13%). Also, feed sampling for nutri-
choice than ignoring or ambiguous crediting of manure ent testing was conducted by off-farm personnel on
nutrients, relying on book values can still be problem- 90% of the farms.
atic because manure nutrient characteristics are often Ration balancing can be a very useful tool in manag-
determined by many site-speciﬁc factors. Substantial ing nutrients on animal farms. Rations may be formu-
discrepancies between book values and direct farm lated based on animal requirements for maintenance
measurements have been reported (e.g., Lindley et al., and production while minimizing excessive N and P
1988; Peters, 2000; Rieck-Hinz et al., 1996). in the diets. Such balanced rations would enhance ani-
Perhaps a major concern hindering some farm advi- mal efﬁciency and minimize nutrient excretion in ma-
sors from recommending manure nutrient testing as nure (Kohn, et al., 1997), beneﬁting both the farm
a routine practice is the common belief that manure economy and the environment. On the other hand,
is heterogeneous in nature and nutrient concentra- rations may be formulated with a wide ‘safety margin’,
tions can vary a great deal. Hence, the potential bene- resulting in excess amounts of nutrients compared
ﬁts in savings on fertilizer costs and (or) reduction of with animal requirements. Excessive nutrients in
environmental nutrient losses may be obscured by the diets often have neither positive nor negative impact
uncertainty of testing results; the expenses in labor, on animal performance but will be excreted in manure
time, and laboratory analysis associated with manure with environmental consequences.
sampling and testing may appear unjustiﬁable. This Balancing rations for optimal dietary P intake is
logistic concern may be addressed by some recent ﬁnd- especially signiﬁcant for P management. Recent sur-
ings. Through intensive and systematic sampling and veys have indicated that dairy producers routinely
testing, Dou et al. (2001) demonstrated that manure overfed cows with P by 20 to 50% (Shaver and Howard,
nutrient variation was largely macro-scale, much of 1995; Sink et al., 2000; Wu et al., 2000) compared with
which could be eliminated through agitation or normal standard recommendations by the National Research
mixing systems used on many farms. For several farms Council (NRC, 1989). Recent studies have demon-
that used agitation or mixing before or during manure strated that feeding lactating cows with P close to or
storage unloading (when serial samples were taken), even slightly less than the NRC recommendations had
a composite of three to ﬁve samples was shown to be no negative impact on milk yield, reproduction efﬁ-
adequate for reliable and accurate testing of N and P. ciency, or other health indices (Valk and Ebek, 1999;
Furthermore, the variation in N and P in the manure Wu and Satter, 2000). If, for instance, ration formula-
samples for the individual manure systems was no tion personnel on farms make their P recommenda-
greater than the variation in soil available nutrients tions based on the NRC standards or animal require-
reported in the literature. The researchers concluded ments, a 30% reduction on total feed P intake could
that to manage the vast amount of manure and nutri- be achieved on an average farm. Such P reduction
ents with environmental responsibility, manure nutri- efforts would not only save producers money (through
ent testing ought to be promoted in the same manner decreasing or even eliminating P supplements, which
as soil nutrient testing is advocated (Dou et al., 2001). are often the most costly feed ingredients) but also
The stakeholders. Soil conservation service and reduce the P management burden, especially for farms
cooperative extension personnel have traditionally with substantial P surplus.
played a major role in providing producers with useful The survey identiﬁed off-farm personnel assisting
information on soil and crop management for sus- farmers in determining fertilizer or manure applica-
tained productivity and erosion and pollution control. tion rates as fertilizer sales representatives (40% of
Modern animal agriculture involves a broader range the farms), crop advisors or independent consultants
of professionals providing farmers with a variety of (31%), nutrient management specialists (5%), exten-
services. These off-farm personnel can have a funda- sion agent/conservation personnel (4%), and producers
mental inﬂuence on farm efﬁciency and nutrient bal- themselves (42%). Also, for manure hauling and
ances through their management advice. This might spreading, contract services were used on 7% of the
Journal of Dairy Science Vol. 84, No. 4, 2001
OUR INDUSTRY TODAY 971
Table 3. Estimated annual nitrogen and phosphorus ﬂows for a unit bility to P loss (Gburek et al., 2000). For these farms,
dairy cow [1000 lb of live weight, i.e., 1 animal equivalent unit (AEU)]
and unit removal (lb/ac) by crops most common in Pennsylvania implementing feeding strategies with optimal dietary
dairies, and approximated ﬁeld nutrient balance at different animal P to minimize P excretion in manure is of vital impor-
densities.1 tance. Exporting manure or identifying additional
N P2O5 land suitable for manure application are viable op-
Animal nutrient requirement, lb/AEU2 318 108
tions. Treating manure before ﬁeld spreading to re-
Manure nutrient for spreading, lb/AEU3 150 60 duce vulnerable P fractions may offer a temporary
Crop nutrient removal, lb/ac4 solution especially when surface spreading outside of
Corn grain 109 40 the growing season is inevitable. There is likely to
Corn silage 106 75
Alfalfa hay 165 50 be an economic cost in implementing environmentally
Nutrient equivalent and balance, lb/ac5 sensitive nutrient management practices on these
1.0 AEU/ac 53 (−)6 60 (+/−) farms (Beegle et al., 2000).
1.5 AEU/ac 79 (−) 90 (+)
2.0 AEU/ac 105 (+/−) 120 (++)
Sixty-eight percent of the surveyed farms had ani-
2.5 AEU/ac 131 (+) 150 (++) mal density lower than 1120 kg of live weight per
3.0 AEU/ac 157 (+) 180 (+++) hectare of cropland (i.e., <1 AEU/ac), with the re-
English units are used in this table to be consistent with other maining 30% falling between 1120 and 2240 kg of live
relevant references (e.g., AEU/ac in PA NM regulations, crop yields, weight per hectare (i.e., 1 to 2 AEU/ac). As indicated
and nutrient removal in lb or bu/ac, etc.). in Table 3, ﬁeld N balance was estimated to be in
Estimated for the average herd of the survey farms with consider-
ation of the relative components of 1 AEU (0.65 lactating cow, 0.08 dry
deﬁcit or near to balance depending on the animal
cow, 0.23 heifer, and 0.03 calf); nutrient requirements are calculated density of individual farms, while P would be near to
based on NRC standards for the relevant animal groups. balance or in slight deﬁcit if animal density was close
Based on Penn State Agronomy Guide (1999 to 2000): 82 lb of to 1 AEU/ac. Substantial P surplus would occur if ani-
manure/AEU per day, manure containing 10 lb of N and 4 lb of
P2O5 per ton. These are estimated quantities of manure and manure mal density departed signiﬁcantly from 1 AEU/ac.
nutrients for ﬁeld application, not fresh excretions. Management tactics that conserve manure N, such as
Average crop yield for the nine counties from 1988 to 1996 (corn incorporating manure soon after surface spreading,
grain 99.3 bu/ac, corn silage 15.1 ton/ac, alfalfa hay 3.3 ton/ac) times and manure testing for accurate nutrient crediting are
nutrient removal per unit harvest crop from The Agronomy Guide
(1 to 1.1 lb of N and 0.4 lb of P2O5 per bushel of corn grain, 7 lb of likely to enhance the economic and agronomic efﬁ-
N and 5.0 lb of P2O5 per ton of corn silage, 50 lb of N and 15 lb of ciency and improve farm proﬁtability with environ-
P2O5 per ton of alfalfa hay). mental beneﬁts. Ration balancing to eliminate excess
Assuming fertilizer equivalent of 0.35 for total N and 1.0 for total
P in manure.
dietary P and reduce P in manure would not only gen-
Minus(−) and plus (+) symbols refer, respectively, to the estimated erate savings for the farmers but also favor long-term
relative deﬁcit or surplus of N and P2O5 for each AEU/ac level. soil P balance.
A point may be made based on the simpliﬁed nutri-
ent ﬂow estimates in Table 3. Even with animal den-
farms; another 15% reported using both contract ser- sity as low as 1 AEU/ac, substantial amounts of off-
vices and farm employees. Clearly, educating off-farm farm nutrients would still be needed to meet animal
advisors along with producers and encouraging the requirements because feeds produced on the farm
full participation of all stakeholders is a key to success would supply only one third to one half of the require-
in sustaining animal agriculture and protecting the ments (106 to 165 lb of N and 40 to 75 lb of P2O5
environment (Beegle et al., 2000). contained in homegrown feeds compared to 318 lb of
Animal density and nutrient balances. Only 2% N and 108 lb of P2O5 as animal requirements; Table
(19 operations) of the surveyed farms fell into the man- 3). Inevitable nutrient losses occur on farms through-
datory category (i.e., >2 AEU/ac) for nutrient manage- out the production processes since dairy cows typically
ment planning and implementation according to Penn- capture only 25 to 35% of dietary N and P, while the
sylvania’s nutrient management regulations. Con- rest is excreted in manure which, in turn, is subject
cerning manure nutrient supply and crop nutrient to various losses. As more demand for accountability
needs in the ﬁeld, N is likely to be near balance on is placed on farmers, society should recognize the
these farms unless the animal density far exceeded 2.0 tradeoffs between a bountiful and inexpensive supply
AEU/ac. However, P surplus likely would be twofold or of high quality animal products and inevitable envi-
even higher on this category of farms as indicated in ronmental consequences. Another point worth men-
Table 3. Clearly, an N-based management approach tioning is that, of the off-farm nutrients brought to
on such farms would lead to P accumulation in soils farms as purchased feeds, a large portion were in by-
with elevated potential of P runoff loss, especially if products or “wastes” of other industries. Examples of
the site is in a critical source area with a high vulnera- such byproducts being used on the survey farms were
Journal of Dairy Science Vol. 84, No. 4, 2001
972 DOU, ET AL.
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ACKNOWLEDGMENTS Domestic Animals, Nutrient Requirements of Dairy Cattle. 6th
ed. Nat. Acad. Sci., Washington, DC.
This survey was supported by a USDA-CSRS grant. Nowak, P., R. Shepard, and F. Madison. 1998. Farmers and manure
We are grateful to the following dairy producers for management: a critical analysis. Pages 1–32 in Animal Waste
their feedback in previewing the questionnaire: Walt Utilization: Effective Use of Manure as a Soil Resource. J. L.
Hatﬁeld and B. A. Stewart, ed. Ann Arbor Press, Chelsea, MI.
Moore, Sam Shotzberger, Paul Clugston, Dan Miller, Peters, J. B. 2000. Manure sampling and testing. Pages 369–379 in
Ken Zurin, and Tom Bollinger. We also thank John D. Proc. Managing Nutrients and Pathogens from Animal Agricul-
Toth for technical assistance. ture. Camp Hill, PA.
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OUR INDUSTRY TODAY 973
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Shaver, R., and W. T. Howard. 1995. Are we feeding too much phos- Meeting Abstracts. ASA-CSSA-SSSA, Madison, WI.
phorus? Hoard’s Dairyman. vol. 140, April 10, 1995 p.280–281. Valk, H, and L.B.J. Ebek. 1999. Inﬂuence of prolonged feeding of
Sims, J. T. 2000. The role of soil testing in environmental risk limited amounts of phosphorus on dry matter intake, milk pro-
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Journal of Dairy Science Vol. 84, No. 4, 2001