Tải bản đầy đủ - 0 (trang)
III. Nitrogen Management for Poultry Wastes

III. Nitrogen Management for Poultry Wastes

Tải bản đầy đủ - 0trang

J. T. SIMS AND D. C. WOLF



24



Uric acid



Urea



Ammonia



Figure 5 Generalized reaction for the conversion of uric acid to ammonia.



chips, etc.). For instance, studies by Ndegwa et al. (1991) showed that the N

concentration in the fine fraction of poultry litter ( 1 0 . 8 3 mm) was greater than

in larger sized particles.



B. NITROGEN

TRANSFORMATIONS

IN STORAGE

AND HANDLING

The majority of N excreted in poultry manure is in the form of uric acid that

can be rapidly converted to urea and NH,-N if temperature, pH, and moisture

are adequate for microbial activity (Bachrach, 1957; Rouf and Lomprey, 1968;

Siege1 et al., 1975). The hydrolysis reactions result in elevated pH levels that

facilitate NH,-N volatilization (Reynolds and Wolf, 1987b). Losses of NH,-N

from poultry wastes begin to occur immediately after excretion and can be influenced by conditions within the production house. For instance, Weaver and

Meijerhof (1991) found that NH,-N losses from broiler litter became greater as

relative humidity in the house increased.

Nitrogen loss during storage and handling is determined by climatic conditions

and the specific manure management system used. Estimates of N loss range from

10 to 80% of the N excreted (Midwest Planning Service, 1985; Soil Conservation

Service, 1992). For poultry litter stored under roofed facilities, estimated losses

during storage and handling are 30 to 45% of the total N content. For manure

diluted by 250% and held in storage ponds or lagoons, the N loss may be 70 to

80% of the total N in the waste. Maximizing the nutrient value of poultry wastes,

therefore, requires the use of management practices that will optimize N conservation during storage and handling (Barrington, 1991).



C . NITROGEN

LOSSESDUETO DRYINGPOULTRY

WASTES

Drying poultry waste will enhance volatization if the conversion of uric acid

and urea to NH,-N is complete. Oven drying fresh poultry manure from a laying



POULTRY WASTE MANAGEMENT



25



hen operation at 66°C resulted in a decrease in the total N level from 5.65 to

4.01% in the wet and dry manure, respectively (Gale et al., 1991). In the wet

manure, 34% of the total N was in the NH4-N form and NO,-N levels were

5 1 mg/kg. When fresh poultry manure was air dried for 10 days, Giddens and

Rao (1975) found that 47.6% of the total N was lost via NH,-N volatilization.

Parker et al. (1959) reported that hen manure and broiler manure lost 17 and

12%, respectively, of their total N when dried for 10 hours at 78°C. In a study

comparing methods of drying poultry litter, Wood and Hall (1991) reported that

up to 15% of the total N was lost during drying. The P, K, Cu, Fe, and Zn levels

were not influenced by drying.

Nitrogen losses during drying influence not only the final N content of

the manure or litter, but the accuracy of manure analyses used to determine

proper field application rates. If laboratories conducting manure analyses dry

samples at different temperatures prior to determination of total N, or do not

dry them at all, they are certain to obtain different analytical results. Combined

with this are possible changes in total N content that occur between the time of

sample collection, analysis, and application due to NH3-N volatilization. This

again illustrates the need to use manure analyses for N as guidelines, not as

absolute values.



D. NITROGEN

TRANSFORMATIONS

IN SOILS

As with most biological systems, the temperature, moisture, and pH of the

system largely determine the biological transformations that occur in soil

amended with poultry waste. When poultry waste is added to soil, mineralization

of organic N and nitrification of NH4-Noccur rapidly under favorable conditions

(Fig. 4). Incorporation of the waste into the soil will result in more rapid conversions than does surface application. Immobilization, NH,-N volatilization,

and denitrification also occur in poultry waste-amended soils.



1. Ammonia Volatilization

Ammonia volatilization during application of poultry waste can result in substantial N losses. Not only does the loss occur during application of the waste,

but NH,-N volatilization continues when the poultry waste is allowed to remain

on the soil surface. The volatilization process depends on conversion of uric acid

to urea and then NH3-N. With adequate moisture and suitable temperature and

pH, the process can be complete within 24 hours (Lacey ef al., 1981). The result

is that as much as 50% of the total N in poultry waste is often in the NH,-N form

(Reddy el al., 1980a).

When poultry waste is surface applied, in excess of 50% of the total N in the



26



J. T. SLMS AND D. C. WOLF



waste material may be lost via volatilization. In laboratory and field studies,

Wolf et al. (1988) found that as much as 37% of the total N in fresh manure

from laying hens could be lost as NH3-N in 5 11 days when the waste was surface

applied to a Bowie fine sandy loam and a Captina silt loam. Studies with 18

broiler litter samples by Schilke-Gartley and Sims (1993) showed that surface

application of the litter resulted in NH,-N volatilization losses of from 4 to 3 1%

of the total N within 12 days (average of 74% of added NH,-N). Immediate

incorporation of the broiler litter reduced average NH,-N volatilization losses

to 3% of total N, relative to 20% for surface application. Most of the NH,-N

volatilization from these broiler litters occurred within 3 days, as illustrated

in Fig. 6 .

High temperatures, moist soil conditions, low hydrogen ion buffering capacity, high pH, and windy conditions can facilitate the gaseous loss of NH,-N

(Adriano et al., 1974; Donovan and Logan, 1983; Muck and Richards, 1983;

Reynolds and Wolf, 1987a). It is also possible that application of poultry waste

to crop residue or forage vegetative cover would enhance NH,-N volatilization

by preventing the poultry waste from coming in contact with the soil (Beyrouty

et al., 1988; Donovan and Logan, 1983; Reynolds and Wolf, 1988). Contact

with the soil allows the NH,-N to be retained on cation exchange sites. Incorporating the poultry waste immediately after application has been shown to reduce

volatilization losses (Giddens and Rao, 1975). Precipitation or irrigation can also



90

-0



a



80



-0



70



.--N

.-



'

I0



I



a



A



A



A



A



k



. ......



A



60

50



I



-0



-0

-0



A



A



A



40



U



A

20



I



0



1



2



3



,



,



4



,



,



5



,



,



,



6



,



,



7



,



,



8



,



,



!



,



,



,



,



9 1 0 1 1 1 2



Time (days)

Figure 6 Patterns of NH3-N loss from surface applications of poultry manure (PM) to a Hammonton loamy sand soil (Schilke-Gartley and Sims. 1993).



27



POULTRY WASTE MANAGEMENT



reduce gaseous losses by transporting the NH,-N into the soil where it can be

retained (Lauer et al., 1976).



2. Mineralization-Nitrification-Immobilization

Mineralization, the conversion of organic N to inorganic N, is critical to providing available forms of N to plants. Predicting the rate and amount of plant

available N produced in poultry waste-amended soils is necessary for proper

plant nutrition and to protect the quality of groundwater and surface water

(Castellanos and Pratt, 1981a; Liebhardt et al., 1979; Pratt et al., 1973; Weil

et al., 1990). Net mineralization of organic N is calculated using Eq. (1).

% Net mineralization =



[(NH,-N



+ NO,-N),



- (NH4-N



+ NO,-N),k



-(NH,-N



+ NO,-N),,,,,]



[(TotalN)wa,Ie- (NH4-N -tNo3-N)wdqte]



x 100

(1)



where (NH,-N),, and (NO,-N),,, are the NH,-N and NO3-N concentrations (in

mg/kg) in the soil treated with poultry waste, (NH,-N),, and (N03-N)ckare

the NH,-N and NO,-N levels in the control (“check”) soils that did not receive poultry waste, and (Total N),,,,, , (NH,-N),,,,, , and (N03-N),,,,, are the

total N, NH,-N, and NO,-N added to the poultry waste at time zero. Selected

mineralization values are given in Table V for poultry manure, litter, and

compost.

Sims (1986b) added three different poultry manures to an Evesboro loamy

sand in a laboratory study and showed that 30-60% of the organic N in two of

the manures was mineralized under favorable moisture conditions in a 150-day

incubation. He also showed that from 7 to 37% of the organic N was mineralized

when the incubations were carried out at 0°C and that increasing the temperature

to 40°C increased net mineralization. Nitrification, the sequential oxidation of

NH t; to NO ;to NO; , was inhibited by moisture stress at 25°C which resulted

in an accumulation of NH,-N. All incubations displayed N immobilization, conversion of inorganic N to organic N in microbial biomass, during the initial phase

of the studies. Nitrogen mineralization in a clay and a sandy soil amended with

ground and pelleted poultry manure was studied by Hadas et al. (1983). Their

results indicated that mineralization was a two-stage process. At 25”C, from 34

to 42% of the total N in the poultry manure was mineralized in the initial rapid

phase. The second phase was a slow-release process, and after 9 to 13 weeks,

42 to 50% of the total N had been mineralized and the authors suggested that

two distinct substrates resulted in the two phases. Incubations were conducted at

14, 25, and 35°C and the results showed that nitrification was inhibited at 14”C,

which resulted in an accumulation of NH4-N in the soil. Bitzer and Sims (1988),



Table V

Selected Net Mineralization Percentages for Poultry Manure, Litter, and Compost



Poultry

waste



Application

rate

(g wasteikg)



mg total N

kg soil



Total N

content



Temperature



mJ)



Soil



C"



Manure



6.5



320



4.93



Evesboro

loamy sand



25



Manure



33.3



1130



3.4



Sandy



25



Manure



33.3



1130



3.4



Clay



25



Litter

(mean of 20)

Manure

(mean of 2)

Manure



3.4



I80



5.32



Kalmia

sandy loam

Norfolk sand



Composted manure

Manure



130

270



4.59



-



270



1.7



45



1700



3.8



San Emigdio

fine sand

San Emigdio

fine sand

Bowie fine

sandy loam



Incubation

time

(days)



Total N

mineralized



(5'~)



Ref.



23



30

90

150

7

90

7

90

140



16

38

40

34

48

38

47

66



20-23



182



42



Chescheir et al. ( 1986)



23



7

70

7

70

14



39

48

18

29

37



Castellanos and Pratt ( 1 98 1 b)



23

25



Sims ( 1986b)



Hadas



ef al.



(1983)



Hadas er al. (1983)

Bitzer and Sims (1988)



Castellanos and Pratt ( 1 98 1 b)



Gilrnour et al. (1987)



POULTRY WASTE MANAGEMENT



29



Manure sample



Figure 7 Timing of N availability when poultry manure is added to a soil. Initial N , represents

NO,-N immediately after extraction; other bars represent net N mineralKC1-extractable NH,-N

ized during 0- 14 and 14-140 days (Bitzer and Sims, 1988).



+



in a study with 20 poultry manures, also reported that mineralization of manure

N occurred in two phases and that, when combined with the immediately available inorganic N in poultry manure, it could result in large accumulations of

available N in the soil within 14 days (Fig. 7).

Studies by Gale and Gilmour (1986) showed that poultry litter decomposition,

as measured by CO, evolution, was a three-phase process. During the initial 7

days of incubation, the rapid phase of mineralization resulted in large increases

in inorganic N levels in a Captina silt loam incubated at 25°C. There was a linear

relationship between net C and net N mineralized during the rapid phase of decomposition. The second or intermediate phase lasted from 7 to 14 days and the

slow phase that began at 14 days showed either no net mineralization or immobilization of N. Chescheir er al. (1986) also suggested that substantial immobilization occurred during the first 14 days in two soils amended with poultry

manure. Because broiler and laying hen manure contains approximately 17, 13,

and 4% by weight hemicellulose, cellulose, and lignin, respectively, it would

appear likely that these materials would be important substrates for microbial

utilization during the slow phase of decomposition (Smith, 1973). During the

rapid, intermediate, and slow phases, the percentages of the litter C evolved as

CO, were 25, 10, and 65%, respectively (Gale and Gilmour, 1986). First-order

rate constants for the rapid phase followed the Arrhenius equation for 11, 18,

and 25°C incubation temperatures.

Nitrification is inhibited by lack of oxygen, low temperature, inadequate moisture, pH values < 5 or >8, and NH,-N toxicity (Alexander, 1977). Accumula-



30



J. T. SIMS AND D. C. WOLF



tion of toxic levels of N02-N has been reported in soils amended with poultry

waste (MacMillan et a f . , 1972; Weil e t a l . , 1979).



3. Denitrification

Denitrification is the conversion of NO: or NO 7 to N, or N,O by microbial

activity. It can be an important, but difficult to quantify, mechanism for N loss

in soils amended with poultry waste. Denitrification losses are greatest in poorly

drained soils with high organic matter content and may be from 50 to 100% of

the inorganic N in the soil (Soil Conservation Service, 1992). Denitrification

losses in animal waste-amended soils have been related to soil texture with values

of 35, 20, 10, and 0% for clay, clay loam, silt loam, and sand, respectively

(Gilbertson and Norstadt, 1979).

In a 7-year field study conducted by Cooper et al. (1984), poultry manure was

incorporated in a Davidson clay loam to provide 25 or 49 Mg total N/ha during

a 5-year period. They found that 51 to 58% of the total N applied could not be

recovered 7 years after initiating the study and hypothesized that denitrification

was the most likely mechanism to account for the N loss. The authors noted that

the soil was waterlogged from April to July, which would have resulted in anaerobic conditions. They also suggested that the application of high rates of

poultry manure could have resulted in sufficient levels of available C to stimulate

microbial activity and denitrification.

Reddy et af. (1980a) conducted laboratory studies to evaluate denitrification

potential in a Norfolk sandy loam amended with 10 g poultry manure/kg soil

and incubated at 22°C. Following 30-, 60-, 90-, or 120-day aerobic incubations,

the soil was saturated with water and the disappearance of NO,-N evaluated. The

results showed that the 30-day aerobic incubation followed by saturated conditions resulted in almost 75% of the NO,-N being lost after 24 hours under anaerobic conditions. The authors concluded that the 60-, 90-, and 120-day aerobic

incubations resulted in depletion of available C and even though NO,-N was

present and the soil was anaerobic, there was not sufficient C available for appreciable denitrification to occur. Meek et a f . (1974) found that annual applications

of cattle manure resulted in less NO,-N leaching to a depth of 80 cm than did

single manure applications. The authors suggested that annual manure applications provided higher levels of soluble organic C that could be used by bacteria

carrying out denitrification.

As was recently noted by Russelle (1992), the ability to predict the influence

of management decisions on N losses in pasture and rangeland has been greatly

hampered by the spatial and temporal variability of N cycling. Additional information on denitrification in manure-soil systems appears to be a critical need

(Bouldin et al., 1984).



31



POULTRY WASTE MANAGEMENT



Mathematical models have been developed to predict how much poultry waste

should be applied to supply crop needs (Mathers and Goss, 1979; Meisinger and

Randall, 1991). To predict plant available N supplied by poultry waste, several

researchers have presented decay coefficients or rate constants (Bitzer and Sims,

1988; Gale and Gilmour, 1986; Gilmour and Gale, 1986; Pratt et al., 1973;

Sims, 1986b). These approaches are discussed in Section VI.



E. CROPRESPONSETO NITROGEN

INPOULTRY

WASTES

1. Forages

Poultry waste is often used as an organic fertilizer in forage production

systems. The addition of poultry waste to tall fescue, orchard grass (Dactylis

gofmerata L.), and bermuda grass has been shown to increase dry matter

production (Fig. 8). In many cases the amount of N applied was in excess of

the amount recommended for forage production and could result in groundwater and surface water contamination. Excessive waste application rates can

result in undesirable effects on the forage crop and the animals consuming the

forage or hay. During a 7-year study in which over 18 Mg/ha-year of broiler

litter was applied to tall fescue used in a grazing study, Stuedemann et al. (1975)

noted problems with grass tetany and fat necrosis, and found NO,-N levels in



c



0'



0



100



200



300



400



500



600



700



800



N Waste Application (kg/ha)

Figure 8 Dry matter production of various forages during the first year following amendment

with poultry waste in nonirrigated field studies. Values were calculated from data taken from Hileman

(1973), Huneycutt et a/. (1988). Quisenberry et al. (1981), and Vandepopuliere et al. (1975). 1,

Fescue with manure; 2, bermuda grass with litter; 3, fescue with litter; 4, orchard grass with litter;

5 , fescue with manure.



32



J. T. SIMS AND D. C. WOLF



the forage of 3300 mg/kg. Based on findings from the research, the authors

concluded that broiler litter should be applied to tall fescue at rates of 5 9 Mg/

ha-year.

In a greenhouse study, Hileman (1971) amended three soils with 11-45 Mg/ha

broiler litter and found that tall fescue would not germinate 2 weeks after the

waste was added, nor would it germinate in two successive planting. He attributed the problem to high salt levels, especially K, and high NH,-N levels attributable to uric acid and urea hydrolysis. Nutrient imbalances in soils amended

with poultry waste could also increase the potential for grass tetany problems

(Wilkinson et al., 1971). Addition of poultry waste has also been shown to result

in the disappearance of legumes in pastures due to the addition of readily available N that would provide a competitive advantage for the grasses (Huneycutt et

al., 1988). These researchers also reported that application of broiler litter at a

rate of 500 kg N/ha-year during the 5-year study resulted in approximately the

same bermuda grass dry matter production as did 224 to 336 kg N/ha of NH,NO,

fertilizer.

Hileman (1973) stated that dry matter production of orchard grass was only

slightly increased by applying more than 9 Mg broiler liter/ha in a 3-year field

study. He also noted that after 3 years of litter application, pH and extractable

Ca levels were decreased and available P and K levels were increased in the soil

(Hileman, 1967a). Vandepopuliere et al. (1975) also noted a decrease in the

soil Ca level with poultry waste application at one site. Soil physical properties

such as decreased bulk density, increased water-holding capacity, and increased

water-stable aggregation are also improved by poultry waste addition to soil

(Hafez, 1974; Weil and Kroontje, 1979).

2. Corn

Corn (Z. mays L.) response to poultry waste addition has been examined

in numerous field studies (Fig. 9). Kalmia and Fallsington sandy loams were

amended with three poultry manures and NH,NO, at rates designed to provide

comparable amounts of plant available N (PAN). For manures, PAN = 80% x

[NH,-N

NO,-N] 60% X [organic N]) of 0,90, 180, and 270 kg/ha (Bitzer

and Sims, 1988). The 2-year average irrigated corn yields for manures at the

three PAN rates were 9.0, 11.O, and 12.3 Mg/ha, compared to 10.9, 12.4, and

12.4 Mg/ha for NH,NO, . Early season leaching losses of NO,-N were suspected

of reducing corn yields with manure at one site relative to NH,NO, , wherein the

majority of N was applied via sidedressing. This study illustrates one of the

major concerns about use of poultry manure as an N source-the decreasing

efficiency of N recovery at higher N rates that may subsequently result in NO,-N

leaching. Consider the fact that increasing PAN from 180 to 270 kg N/ha in-



+



+



33



POULTRY WASTE MANAGEMENT



- Kalmla



* Fallslngton * Elkton



*Cecil



* Evesboro

~



0



1,000



~~~



2,000



3,000



Plant Available N (kg/ha)

Figure 9 Influence of poultry waste additions on corn yields in five soils. Values were calculated

from data taken from Bitzer and Sims (1988), Carreker er af. (1973), Shortall and Liebhardt (1975),

and Sims (1987).



creased yields by only 1.3 Mg/ha in this study for poultry manure, and not at

all for NH,NO,. It should also be noted that the difference in actual rate of

poultry manure applied to provide these two N rates was relatively small: 4.2

and 6.3 Mg/ha. Rates greater than 6 Mg/ha are commonly applied in Delaware

due to improperly calibrated application equipment or by farmers with inadequate land for manure use at lower, currently recommended manure application

rates (4-5 Mg/ha). Similar results were obtained on an Evesboro loamy sand

soil by Sims (1987), where poultry manure was compared with NH,NO, as an

N source for conventional (CT) and no-tillage (NT) irrigated corn. In all cases,

the highest corn yields were obtained with the highest rate of manure addition

studied, but efficiency of N recovery by the crop decreased markedly as N rate

increased. The 3-year average efficiencies for N recovery for poultry manure at

rates of 84, 168, and 252 kg PAN/ha were 50, 37, and 36% (CT) and 31, 28,

and 31% (NT).

When poultry waste has been applied at excessive rates, corn yields have been

reduced and high N03-N levels have been found in groundwater (Carreker et al.,

1973; Shortall and Liebhardt, 1975; Wed et al., 1990). Studies demonstrating

the impact of poultry manure on groundwaters were mentioned in Section I. The

recent work of Weil et al. (1990) and ongoing studies by Sims et al. (1991)

further illustrate the potential impact of poultry waste applications on NO; nitrogen concentrations in groundwaters (Fig. 10). The toxicity of high levels of

poultry waste has been related to excessive soluble salts, especially K, NO,-N,

and NH3-H (Liebhardt, 1976; MacMillan et al., 1972; Weil e l al., 1979). Toxicity symptoms exhibited were reduced germination, burned leaf tips and mar-



J. T. SIMS AND D. C. WOLF



lo



-I



25



--c- Poultry manure

I.

Urea

. a. . Control (ON)



A



20



I



15



10



1989



1990



1991



...- .....

Figure 10 Groundwater NO,-N concentrations in the shallow water table of the Atlantic Coastal

Plain of the United States. (A) Groundwater NO,-N concentrations in manured and nonmanured,

irrigated, commercial corn fields (Weil et al., 1990). (B) Effect of applications of poultry manure

and urea at 224 kg N/ha year on groundwater NO,-N levels, relative to an unfertilized treatment

(J. T. Sims, unpublished data).



Tài liệu bạn tìm kiếm đã sẵn sàng tải về

III. Nitrogen Management for Poultry Wastes

Tải bản đầy đủ ngay(0 tr)

×