Minimum tillage practices used in dryland cropping systems that reduce soil water evaporation and erosion may also decrease efficiency of manure nutrient utilization. We initiated a study in 1997 to investigate the effects of surface-applied stockpiled and composted beef cattle (Bos taurus) manure on soil N and sorghum [Sorghum bicolor (L.) Moench] and wheat (Triticum aestivum L.) yields and N-uptake within a wheat-sorghum-fallow dryland crop rotation. Paired terraces with no-tillage (NT) and stubble-mulch tillage (ST) systems were main plots of a single rotation phase. Stockpiled manure, composted manure, or commercial fertilizer (urea + ammonium phosphate) were applied prior to sorghum planting to supply estimated Nand P requirements of sorghum and wheat for a 3- year period. Phosphorus-based manure or compost treatments also received supplemental urea. Unfertilized treatment checks were included for yield and nutrient comparisons. Sorghum grain yield in 1999 exhibited a significant (P \u3c 0.05) response to tillage and fertilizer treatments. Plots receiving urea had 22% greater yield and 16% greater N-uptake than manure and compost amended plots. Moreover, manure and compost sorghum yields were no different or slightly lower than those of the unfertilized plots. Wheat was a good scavenger of residual N accumulated throughout the fallow period although grain yield was not affected by N treatments and tillage. Residual NO3--N after harvest and N-uptake were significantly greater under ST as compared with NT. Tillage may be required to maintain higher mineralization rates and permit a more efficient use of manure N

Baumhardt, R.L.

Dao, T.H.

Schwartz, R. C.

English

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Publications from USDA-ARS / UNL Faculty U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska 2002 Tillage And Beef Cattle Manure Effects On Soil Nitrogen In A Dryland Rotation R. C. Schwartz USDA-ARS, robert.schwartz@ars.usda.gov R.L. Baumhardt USDA-ARS T.H. Dao USDA-ARS, thanh.dao@ars.usda.gov Follow this and additional works at: https://digitalcommons.unl.edu/usdaarsfacpub  Part of the Agricultural Science Commons Schwartz, R. C.; Baumhardt, R.L.; and Dao, T.H., "Tillage And Beef Cattle Manure Effects On Soil Nitrogen In A Dryland Rotation" (2002). Publications from USDA-ARS / UNL Faculty. 1062. https://digitalcommons.unl.edu/usdaarsfacpub/1062 This Article is brought to you for free and open access by the U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Publications from USDA-ARS / UNL Faculty by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. TILLAGE AND BEEF CATTLE MANURE EFFECTS ON SOIL NITROGEN IN A DRYLAND ROTATION R.c. Schwartz, R.L. Baumhardt, and T.H. Dao USDA-ARS, Bushland, TX rschwart@cprI.ars.usda.gov, (806) 356-5762 ABSTRACT Minimum tillage practices used in dryland cropping systems that reduce soil water evaporation and erosion may also decrease efficiency of manure nutrient utilization. We initiated a study in 1997 to investigate the effects of surface-applied stockpiled and composted beef cattle (Bos taurus) manure on soil N and sorghum [Sorghum bicolor (L.) Moench] and wheat (Triticum aestivum L.) yields and N-uptake within a wheat-sorghum-fallow dryland crop rotation. Paired terraces with no-tillage (NT) and stubble-mulch tillage (ST) systems were main plots of a single rotation phase. Stockpiled manure, composted manure, or commercial fertilizer (urea + ammonium phosphate) were applied prior to sorghum planting to supply estimated Nand P requirements of sorghum and wheat for a 3-year period. Phosphorus-based manure or compost treatments also received supplemental urea. Unfertilized treatment checks were included for yield and nutrient comparisons. Sorghum grain yield in 1999 exhibited a significant (P < 0.05) response to tillage and fertilizer treatments. Plots receiving urea had 22% greater yield and 16% greater N-uptake than manure and compost amended plots. Moreover, manure and compost sorghum yields were no different or slightly lower than those of the unfertilized plots. Wheat was a good scavenger of residual N accumulated throughout the fallow period although grain yield was not affected by N treatments and tillage. Residual NO,--N after harvest and N-uptake were significantly greater under ST as compared with NT. Tillage may be required to maintain higher mineralization rates and permit a more efficient use of manure N. INTRODUCTION In many regions dominated by animal-based agriculture, confined animal feeding operations generate large quantities of manure and animal-by products that must be properly managed to minimize or avoid offsite impacts to water bodies. Land application is the most economically viable alternative to utilize manure and manure by-products. Manure utilization as a nutrient source for crops is hampered because its fertilizer equivalency may change over time and the nutrient availability depends on the manure and soil characteristics as well as biological and chemical transformations within the soil system. Moreover, prolonged applications of manure with low N:P ratios can lead to P loading and increase the potential for excessive loss of P in surface runoff. Difficulties with manure use for dryland crops in semiarid environments may be further compounded by shallow or no-tillage practices employed to retain surface residues and conserve stored water for crop production. Incorporation of solid manures using inversion tillage may improve the efficiency of manure nutrient utilization but forfeit benefits associated with minimum tillage practices such as reduced evaporation, soil erosion, and runoff (Jones et aI. 1994). Alternatively, manure that is spread and left unincorporated will elevate soil phosphorus levels near the soil surface and increase the likelihood of excessive P losses into surface waters (Smith et aI., 2001). 66 Proceedings of the Great Plains Soil Fertility Conference, Denver, Colorado, March 5-6, 2002, ed. Alan J. Schlegel. We initiated a study in 1997 to investigate the long-term effects of surface-applied stockpiled and compos ted beef cattle manure on soil nitrogen and phosphorus, grain yield, and crop uptake within a wheat-sorghum-fallow dryland crop rotation under NT and ST environments. We present results pertaining to the tillage and manure effects on soil N and plant uptake of N for all rotational phases in 1999 and 2000. MATERIALS AND METHODS The study was established in 1997 on six contour-farmed level terraces on Pullman clay loam (fine, mixed, superactive, thermic Torrertic Paleustoll) near Bushland, TX with an average annual precipitation of 476 mm. Terraces have been cropped under a wheat-sorghum-fallow rotation since 1988. The terraces are managed under no-tillage (NT) or stubble-mulch tillage (ST) (Jones and Popham, 1997) such that all phases of the rotation are present under each tillage treatment every year. The study area had a baseline 8.35 (NT) and 8.13 (ST) g ktl organic carbon for the 0-30 cm soil depth increment with C:N ratios averaging 10.3. Six fertility treatments were established within a randomized split plot design with three replications within each tillage x rotation phase combination. Experimental plots (13.5 x 30 m) within each terrace interval were subdivided with earthen berms perpendicular to the slope to prevent runoff from entering plots. Fertilizers were applied once for each cycle of the rotation in June prior to sorghum establishment. The six treatments were: (1) beef feedyard manure applied to provide 134 kg total N ha-1 (MN); (2) beef feedyard manure applied to provide 16 kg total P ha- 1 plus supplemental urea (MP) (3) composted beeffeedyard manure applied to provide 134 kg total N ha- 1 (CN); (4) composted beef feedyard manure applied to provide 16 kg P ha- 1 plus supplemental urea (CP); (S) urea and ammonium phosphate applied at rates to achieve 108 kg N ha-1 and 20 kg P ha- 1, respectively (CF); and (6) check with no commercial fertilizer or manure applications (CK). Manure and compost applications were made using a modified dry fertilizer drop spreader. Stockpiled beef feedyard manure and commercially composted manure from the same feedyard were collected in the spring of each year. Organic materials were ground using a tub grinder to improve material uniformity and improve uniformity of spreader applications. Applications were not incorporated, however, some shallow « 1 0 cm) incorporation was attained on ST plots with sweep tillage necessary to control weeds after sorghum harvest and later in the rotation. Urea fertilizer was broadcast on the MP, CP, and CF plots at the same time as manure and compost applications. Monoammonium phosphate (11-S2-0) was applied with urea to achieve the desired Nand Prates in the CF plots. Application rates for each treatment averaged across terraces and years are shown in Table 1. Sorghum (DeKalb 39Y) was sown in late June or early July at a rate of 84000 seed ha- 1 and a row spacing of 0.76 m with a vacuum seeder. Winter wheat (TAM 107) was sown in late September or October at a rate of 40 kg ha- 1 in 0.30 m rows with a hoe-drill. Weed control and seedbed preparation in the ST plots were achieved using a sweep plow with one 1.S-m blade and two 1.8-m blades. Herbicide applications were used to control weeds in the NT plots. Immediately prior to grain harvest, sorghum was hand harvested from two 3-m rows and wheat was hand harvested from two I-m rows. Hand samples were dried in a 70° C oven and weighed to determine grain yield and aboveground biomass. After crop harvest or in August for the fallow rotation phase, eight soil samples were collected from each experimental plot and compo sited across the O-S, S-1 0, 10-20, and 20 to 30-cm depth increments. All soil and plant sampling began in 1999. 67 Table 1. Average nitrogen and phosphorus application rates by source and fertilizer treatment, 1997-2001. Treatment Manure, N-based (MN) Manure, P-based (MP) Compost, N-based (CN) Compost, P-based (CP) Commercial Fertilizer (CF) N Source Manure kg N ha- 1 134 49 134 38 Commercial kg N ha- 1 88 103 108 P Source Manure kg P ha- 1 45 16 58 16 Commercial kg P ha- 1 20 Total Nand C in manures, plant tissues, and soils were determined by dry combustion. Soil samples were analyzed for 2M KCI extractable N03--N and NH/-N (Keeney and Nelson, 1982). Ammonium in extracts were determined using the salicylic analog of the indophenol blue blue method (EPA, 1983). Nitrates and nitrites in the extracting solutions were determined using the autoanalyzer - cadmium reduction procedure (EPA, 1983). Mixed linear model analysis (Littell, 1996) with fertilizer treatment and tillage as fixed effects and plot replicates as random effects were used to analyze plant and soil data. The different phases of the rotation represented by three sets of paired terraces were analyzed separately because treatments were not applied at the same time. Orthogonal contrasts were used to determine differences between groups of treatments and effects with P :<; 0.05 were declared significant. RESUL TS AND DISCUSSION Yield and Plant Uptake of Nitrogen Wheat grain yield did not exhibit any response to tillage or fertility treatments in 1999 and 2000 (Fig. 1). However, CF, MP, and CP plots receiving urea two years earlier had greater plant uptake ofN (Fig 2) principally due to significantly higher nitrogen contents in the grain. In addition, stubble mulch tillage (ST) plots yielded grain with, on average, 19% greater nitrogen contents than no-tillage (NT) plots. Sorghum grain yields on NT plots were significantly greater than ST plots in 1999 and 2000. In 1999 sorghum grain yield exhibited a significant response to fertilizer treatments (Fig. 1). Plots that received urea (CF, MP, and CP) had 22% greater yields than MN and CN plots (P=0.0002). However, the relative yield response due to fertilizer source was 7% greater under NT as compared to ST plots. An exceptionally dry growing season in 2000 (-100 mm) caused soil water to be limiting and likely offset any yield responses due to fertilizer treatments. Total N-uptake by sorghum in 1999 was also significantly influenced by tillage. Averaged across fertilizer treatments, N -uptake in stubble mulch tillage plots averaged 31 % greater than no-tillage plots (Fig. 2) despite the fact that grain yields in no-tillage plots were greater. In 2000, sorghum uptake of N was not influenced by tillage. In both years, however, plant uptake ofN in MP, CP, and CF plots receiving urea was 21 % 5000 -, m J: 4000 Cl ~ '0 3000 'ii :;: 2000 .S: m ... C!) 1000 0 Wheat, 2000 MN MP CN CP c::=J NT _ST CF CK Sorghum, 1999 T c:::J NT _ST MN MP CN CP CF CK Treatment Treatment Fig. 1. Mean wheat and sorghum grain yields (dry weight) for the manure, compost, and fertilizer treatments under no-tillage and stubble-mulch tillage. Bars are standards errors. -, m J: 180 150 Cl 120 ~ 1 90 m -g. 60 z 30 o Wheat, 2000 c::=J NT _ST MN MP CN CP CF CK Treatment Sorghum, 1999 c:::J NT _ST MN MP CN CP CF CK Treatment Fig. 2. Mean uptake of N by wheat and sorghum from manure, compost and fertilizer treatments under no-tillage and stubble mulch tillage. Bars are standard errors. greater (P = 0.033) than N-uptake in MN and CN plots. The differential N-uptake among fertility treatments was approximately four-times greater under NT as compared to ST for these two years. Soil Nitrogen Total soil nitrogen was governed principally by soil depth and tillage. When integrated over 30 em, however, total C and N for each tillage treatment were essentially equivalent. Soil NH4 +-N was not significantly influenced by tillage and fertility treatments. The overriding effect of tillage and fertility treatments on soil N were their influence on NO, ~ -N levels. Residual NO, -N was consistently and significantly greater in ST plots as compared with NT plots for all three terraces throughout the duration of the study (Fig. 3). In plots receiving urea (MP, CP, and CF) residual NO, ~ -N was consistently greater than levels in plots that receiving exclusively organic N sources (MN and CN). Comparison of NT and ST residual N03 ~ - N levels in manured plots (CN and MN) four months after application (see Fig. 3, NT and ST Sorghum 2000) suggest that, as expected, ST 69 0 5 E (,) 10 ..c: -Co 15 Q) 0 0 20 en 25 30 0 5 E (,) 10 ..c: -Co 15 Q) 0 0 20 en 25 30 0 5 10 15 --.- MN --0 - MP -CN --E}- CP - -£,- - CF -'f'- CK NT Wheat, 2000 ST Wheat, 2000 20 25 30 o 5 0p ... 8. __ o ',t;] , . ' . ' .' ' ..... --of',. NT Sorghum, 2000 .. , . , . .. ~:8 .::::::::::--;;;;;: .. ST Sorghum, 2000 10 15 20 -1 N03-N, mg kg 25 30 Fig_ 3_ Depth profiles of mean soil N03--N in June 2000 after wheat harvest and in November 2000 after sorghum harvest. All contrasts of the effect of organic (MN, CN) versus commercial urea fertilizer (MP, CP, CF) were significant at the 0_05 level at all depths for these data sets. promoted a greater N mineralization of both manures and native soil organic matter, especially near the soil surface. Low residual N03 - -N after wheat (Fig. 3) coupled with twice as much NO, --N near the surface during the previous fallow (not shown) suggests that wheat behaved as a good scavenger of soil nitrates accumulated over the fallow phase. The above relationships between sorghum yield, N-uptake, and residual nitrate concentrations suggests mineralization of N is slower under NT than ST. Hence, under NT, nitrogen may have limited sorghum grain yield in 1999 for the plots that only received manure or compost as the nitrogen source. Above average growing season precipitation in 1999 may have also caused greater losses of applied and native sources of nitrates in NT plots via runoff and leaching (Eck and Jones, 1992; Jones et aI., 1995). However, accumulation ofN03 --N near the soil surface in 2000 under ST (Fig. 3) suggests that mineralization was greater in these plots during this particularly dry growing season. 70 CONCLUSIONS Greater uptake of N by wheat and sorghum in conjunction with higher levels of residual nitrates in ST plots as compared with NT indicate mineralization of soil organic matter proceeded at a more rapid rate under ST. Plots receiving urea had significantly greater sorghum yields and N-uptake than manure and compost amended plots. Sorghum grain yield response to fertilizer treatments was reduced under ST as compared to NT due to the higher levels of residual NO~ --N near the surface and possibly at greater depths. Sweep-tillage may be required to maintain higher mineralization rates to permit a more efficient use of manure nitrogen. However, nitrogen requirements under ST are not as great as compared to NT due to greater water economy with NT. ACKNOWLEDGMENTS The authors gratefully acknowledge the technical assistance of Jourdan Bell and statistical advice of Tom Popham. REFERENCES Eck, H.V. and O.R Jones. 1992. Soil nitrogen status as affected by tillage, crops, and crop sequences. Agron. J. 84:660-668. EPA, 1983. Methods for chemical analysis for water and wastes. EP A/6/4-79-020. US Govt. Printing Office, Washington, D.C. Jones, O.R, V.L. Hauser, and T.W. Popham. 1994. No-tillage effects on infiltration, runoff, and water conservation on dryland. Trans. ASAE 37:473-479. Jones, O.R and T.W. Popham. 1997. Cropping and tillage systems for dryland grain production in the Southern High Plains. Agron. J. 89:222-232. Jones O.R, S.J. Smith, L.M. Southwick and AN. Sharpley. 1995. Environmental impacts of dryland residue management systems in the southern High Plains. 1. Environ. Qual. 24:453-460. Keeney D.R and D.W. Nelson. 1982. Nitrogen-Inorganic forms. pp 643-698. In: AL. Page, RH. Miller, and D.R Keeney (Eds.) Methods of soil analysis part 2. Chemical and microbiological properties. 2nd Ed. Am. Soc. Agron., Madison, WI. Littell, Re., G.AMilliken, W.W. Stroup, RD. Wolfinger. 1996. SAS system for mixed models. SAS Institute Inc., Cary, NC, USA Smith, D.R, P.A Moore, e.L. Griffis, T.C. Daniel, D.R Edwards, and D.L. Boothe. 2001. Effects of alum and aluminum chloride on phosphorus runoff from swine manure. J. Environ. Qual. 30:992-998. 71 

Tillage And Beef Cattle Manure Effects On
Soil Nitrogen In A Dryland Rotation

UNL | Libraries

University of Nebraska - Lincoln 
DigitalCommons@University of Nebraska - Lincoln 
Publications from USDA-ARS / UNL Faculty U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska 
2002 
Tillage And Beef Cattle Manure Effects On Soil Nitrogen In A 
Dryland Rotation 
R. C. Schwartz 
USDA-ARS, robert.schwartz@ars.usda.gov 
R.L. Baumhardt 
USDA-ARS 
T.H. Dao 
USDA-ARS, thanh.dao@ars.usda.gov 
Follow this and additional works at: https://digitalcommons.unl.edu/usdaarsfacpub 
 Part of the Agricultural Science Commons 
Schwartz, R. C.; Baumhardt, R.L.; and Dao, T.H., "Tillage And Beef Cattle Manure Effects On Soil Nitrogen 
In A Dryland Rotation" (2002). Publications from USDA-ARS / UNL Faculty. 1062. 
https://digitalcommons.unl.edu/usdaarsfacpub/1062 
This Article is brought to you for free and open access by the U.S. Department of Agriculture: Agricultural Research 
Service, Lincoln, Nebraska at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in 
Publications from USDA-ARS / UNL Faculty by an authorized administrator of DigitalCommons@University of 
Nebraska - Lincoln. 
TILLAGE AND BEEF CATTLE MANURE EFFECTS ON 
SOIL NITROGEN IN A DRYLAND ROTATION 
R.c. Schwartz, R.L. Baumhardt, and T.H. Dao 
USDA-ARS, Bushland, TX 
rschwart@cprI.ars.usda.gov, (806) 356-5762 
ABSTRACT 
Minimum tillage practices used in dryland cropping systems that reduce soil water evaporation and 
erosion may also decrease efficiency of manure nutrient utilization. We initiated a study in 1997 to 
investigate the effects of surface-applied stockpiled and composted beef cattle (Bos taurus) manure 
on soil N and sorghum [Sorghum bicolor (L.) Moench] and wheat (Triticum aestivum L.) yields and 
N-uptake within a wheat-sorghum-fallow dryland crop rotation. Paired terraces with no-tillage (NT) 
and stubble-mulch tillage (ST) systems were main plots of a single rotation phase. Stockpiled 
manure, composted manure, or commercial fertilizer (urea + ammonium phosphate) were applied 
prior to sorghum planting to supply estimated Nand P requirements of sorghum and wheat for a 3-
year period. Phosphorus-based manure or compost treatments also received supplemental urea. 
Unfertilized treatment checks were included for yield and nutrient comparisons. Sorghum grain yield 
in 1999 exhibited a significant (P < 0.05) response to tillage and fertilizer treatments. Plots receiving 
urea had 22% greater yield and 16% greater N-uptake than manure and compost amended plots. 
Moreover, manure and compost sorghum yields were no different or slightly lower than those of the 
unfertilized plots. Wheat was a good scavenger of residual N accumulated throughout the fallow 
period although grain yield was not affected by N treatments and tillage. Residual NO,--N after 
harvest and N-uptake were significantly greater under ST as compared with NT. Tillage may be 
required to maintain higher mineralization rates and permit a more efficient use of manure N. 
INTRODUCTION 
In many regions dominated by animal-based agriculture, confined animal feeding operations 
generate large quantities of manure and animal-by products that must be properly managed to 
minimize or avoid offsite impacts to water bodies. Land application is the most economically viable 
alternative to utilize manure and manure by-products. Manure utilization as a nutrient source for 
crops is hampered because its fertilizer equivalency may change over time and the nutrient 
availability depends on the manure and soil characteristics as well as biological and chemical 
transformations within the soil system. Moreover, prolonged applications of manure with low N:P 
ratios can lead to P loading and increase the potential for excessive loss of P in surface runoff. 
Difficulties with manure use for dryland crops in semiarid environments may be further 
compounded by shallow or no-tillage practices employed to retain surface residues and conserve 
stored water for crop production. Incorporation of solid manures using inversion tillage may improve 
the efficiency of manure nutrient utilization but forfeit benefits associated with minimum tillage 
practices such as reduced evaporation, soil erosion, and runoff (Jones et aI. 1994). Alternatively, 
manure that is spread and left unincorporated will elevate soil phosphorus levels near the soil surface 
and increase the likelihood of excessive P losses into surface waters (Smith et aI., 2001). 
66 
Proceedings of the Great Plains Soil Fertility Conference, 
Denver, Colorado, March 5-6, 2002, ed. Alan J. Schlegel. 
We initiated a study in 1997 to investigate the long-term effects of surface-applied stockpiled 
and compos ted beef cattle manure on soil nitrogen and phosphorus, grain yield, and crop uptake 
within a wheat-sorghum-fallow dryland crop rotation under NT and ST environments. We present 
results pertaining to the tillage and manure effects on soil N and plant uptake of N for all rotational 
phases in 1999 and 2000. 
MATERIALS AND METHODS 
The study was established in 1997 on six contour-farmed level terraces on Pullman clay loam 
(fine, mixed, superactive, thermic Torrertic Paleustoll) near Bushland, TX with an average annual 
precipitation of 476 mm. Terraces have been cropped under a wheat-sorghum-fallow rotation since 
1988. The terraces are managed under no-tillage (NT) or stubble-mulch tillage (ST) (Jones and 
Popham, 1997) such that all phases of the rotation are present under each tillage treatment every 
year. The study area had a baseline 8.35 (NT) and 8.13 (ST) g ktl organic carbon for the 0-30 cm 
soil depth increment with C:N ratios averaging 10.3. 
Six fertility treatments were established within a randomized split plot design with three 
replications within each tillage x rotation phase combination. Experimental plots (13.5 x 30 m) 
within each terrace interval were subdivided with earthen berms perpendicular to the slope to prevent 
runoff from entering plots. Fertilizers were applied once for each cycle of the rotation in June prior 
to sorghum establishment. The six treatments were: (1) beef feedyard manure applied to provide 134 
kg total N ha-1 (MN); (2) beef feedyard manure applied to provide 16 kg total P ha- 1 plus 
supplemental urea (MP) (3) composted beeffeedyard manure applied to provide 134 kg total N ha- 1 
(CN); (4) composted beef feedyard manure applied to provide 16 kg P ha- 1 plus supplemental urea 
(CP); (S) urea and ammonium phosphate applied at rates to achieve 108 kg N ha-1 and 20 kg P ha- 1, 
respectively (CF); and (6) check with no commercial fertilizer or manure applications (CK). 
Manure and compost applications were made using a modified dry fertilizer drop spreader. 
Stockpiled beef feedyard manure and commercially composted manure from the same feedyard were 
collected in the spring of each year. Organic materials were ground using a tub grinder to improve 
material uniformity and improve uniformity of spreader applications. Applications were not 
incorporated, however, some shallow « 1 0 cm) incorporation was attained on ST plots with sweep 
tillage necessary to control weeds after sorghum harvest and later in the rotation. Urea fertilizer was 
broadcast on the MP, CP, and CF plots at the same time as manure and compost applications. 
Monoammonium phosphate (11-S2-0) was applied with urea to achieve the desired Nand Prates 
in the CF plots. Application rates for each treatment averaged across terraces and years are shown 
in Table 1. 
Sorghum (DeKalb 39Y) was sown in late June or early July at a rate of 84000 seed ha- 1 and 
a row spacing of 0.76 m with a vacuum seeder. Winter wheat (TAM 107) was sown in late 
September or October at a rate of 40 kg ha- 1 in 0.30 m rows with a hoe-drill. Weed control and 
seedbed preparation in the ST plots were achieved using a sweep plow with one 1.S-m blade and two 
1.8-m blades. Herbicide applications were used to control weeds in the NT plots. Immediately prior 
to grain harvest, sorghum was hand harvested from two 3-m rows and wheat was hand harvested 
from two I-m rows. Hand samples were dried in a 70° C oven and weighed to determine grain yield 
and aboveground biomass. After crop harvest or in August for the fallow rotation phase, eight soil 
samples were collected from each experimental plot and compo sited across the O-S, S-1 0, 10-20, and 
20 to 30-cm depth increments. All soil and plant sampling began in 1999. 
67 
Table 1. Average nitrogen and phosphorus application rates by source and fertilizer treatment, 1997-
2001. 
Treatment 
Manure, N-based (MN) 
Manure, P-based (MP) 
Compost, N-based (CN) 
Compost, P-based (CP) 
Commercial Fertilizer (CF) 
N Source 
Manure 
kg N ha- 1 
134 
49 
134 
38 
Commercial 
kg N ha- 1 
88 
103 
108 
P Source 
Manure 
kg P ha- 1 
45 
16 
58 
16 
Commercial 
kg P ha- 1 
20 
Total Nand C in manures, plant tissues, and soils were determined by dry combustion. Soil 
samples were analyzed for 2M KCI extractable N03--N and NH/-N (Keeney and Nelson, 1982). 
Ammonium in extracts were determined using the salicylic analog of the indophenol blue blue 
method (EPA, 1983). Nitrates and nitrites in the extracting solutions were determined using the 
autoanalyzer - cadmium reduction procedure (EPA, 1983). 
Mixed linear model analysis (Littell, 1996) with fertilizer treatment and tillage as fixed 
effects and plot replicates as random effects were used to analyze plant and soil data. The different 
phases of the rotation represented by three sets of paired terraces were analyzed separately because 
treatments were not applied at the same time. Orthogonal contrasts were used to determine 
differences between groups of treatments and effects with P :<; 0.05 were declared significant. 
RESUL TS AND DISCUSSION 
Yield and Plant Uptake of Nitrogen 
Wheat grain yield did not exhibit any response to tillage or fertility treatments in 1999 and 
2000 (Fig. 1). However, CF, MP, and CP plots receiving urea two years earlier had greater plant 
uptake ofN (Fig 2) principally due to significantly higher nitrogen contents in the grain. In addition, 
stubble mulch tillage (ST) plots yielded grain with, on average, 19% greater nitrogen contents than 
no-tillage (NT) plots. 
Sorghum grain yields on NT plots were significantly greater than ST plots in 1999 and 2000. 
In 1999 sorghum grain yield exhibited a significant response to fertilizer treatments (Fig. 1). Plots 
that received urea (CF, MP, and CP) had 22% greater yields than MN and CN plots (P=0.0002). 
However, the relative yield response due to fertilizer source was 7% greater under NT as compared 
to ST plots. An exceptionally dry growing season in 2000 (-100 mm) caused soil water to be 
limiting and likely offset any yield responses due to fertilizer treatments. Total N-uptake by sorghum 
in 1999 was also significantly influenced by tillage. Averaged across fertilizer treatments, N -uptake 
in stubble mulch tillage plots averaged 31 % greater than no-tillage plots (Fig. 2) despite the fact that 
grain yields in no-tillage plots were greater. In 2000, sorghum uptake of N was not influenced by 
tillage. In both years, however, plant uptake ofN in MP, CP, and CF plots receiving urea was 21 % 
5000 
-
, 
m 
J: 4000 
Cl 
~ 
'0 3000 
'ii 
:;: 
2000 
.S: 
m 
... 
C!) 1000 
0 
Wheat, 2000 
MN MP CN CP 
c::=J NT 
_ST 
CF CK 
Sorghum, 1999 
T 
c:::J NT 
_ST 
MN MP CN CP CF CK 
Treatment Treatment 
Fig. 1. Mean wheat and sorghum grain yields (dry weight) for the manure, compost, and fertilizer 
treatments under no-tillage and stubble-mulch tillage. Bars are standards errors. 
-
, 
m 
J: 
180 
150 
Cl 120 
~ 
1 90 
m 
-g. 60 
z 
30 
o 
Wheat, 2000 c::=J NT 
_ST 
MN MP CN CP CF CK 
Treatment 
Sorghum, 1999 c:::J NT 
_ST 
MN MP CN CP CF CK 
Treatment 
Fig. 2. Mean uptake of N by wheat and sorghum from manure, compost and fertilizer treatments 
under no-tillage and stubble mulch tillage. Bars are standard errors. 
greater (P = 0.033) than N-uptake in MN and CN plots. The differential N-uptake among fertility 
treatments was approximately four-times greater under NT as compared to ST for these two years. 
Soil Nitrogen 
Total soil nitrogen was governed principally by soil depth and tillage. When integrated over 
30 em, however, total C and N for each tillage treatment were essentially equivalent. Soil NH4 +-N 
was not significantly influenced by tillage and fertility treatments. The overriding effect of tillage 
and fertility treatments on soil N were their influence on NO, ~ -N levels. Residual NO, -N was 
consistently and significantly greater in ST plots as compared with NT plots for all three terraces 
throughout the duration of the study (Fig. 3). In plots receiving urea (MP, CP, and CF) residual 
NO, ~ -N was consistently greater than levels in plots that receiving exclusively organic N sources 
(MN and CN). Comparison of NT and ST residual N03 ~ - N levels in manured plots (CN and MN) 
four months after application (see Fig. 3, NT and ST Sorghum 2000) suggest that, as expected, ST 
69 
0 
5 
E 
(,) 10 
..c: 
-Co 15 Q) 
0 
0 20 
en 
25 
30 
0 
5 
E 
(,) 10 
..c: 
-Co 15 Q) 
0 
0 20 
en 
25 
30 
0 5 10 15 
--.- MN 
--0 - MP 
-CN 
--E}- CP 
- -£,- - CF 
-'f'- CK 
NT Wheat, 2000 
ST Wheat, 2000 
20 25 30 o 5 
0p ... 8. __ 
o ',t;] 
, 
. ' 
. ' 
.' 
' ..... 
--of',. 
NT Sorghum, 2000 
.. 
, . 
, . 
.. ~:8 
.::::::::::--
;;;;;: .. 
ST Sorghum, 2000 
10 15 20 
-1 
N03-N, mg kg 
25 30 
Fig_ 3_ Depth profiles of mean soil N03--N in June 2000 after wheat harvest and in November 2000 
after sorghum harvest. All contrasts of the effect of organic (MN, CN) versus commercial urea 
fertilizer (MP, CP, CF) were significant at the 0_05 level at all depths for these data sets. 
promoted a greater N mineralization of both manures and native soil organic matter, especially near 
the soil surface. Low residual N03 - -N after wheat (Fig. 3) coupled with twice as much NO, --N near 
the surface during the previous fallow (not shown) suggests that wheat behaved as a good scavenger 
of soil nitrates accumulated over the fallow phase. 
The above relationships between sorghum yield, N-uptake, and residual nitrate concentrations 
suggests mineralization of N is slower under NT than ST. Hence, under NT, nitrogen may have 
limited sorghum grain yield in 1999 for the plots that only received manure or compost as the 
nitrogen source. Above average growing season precipitation in 1999 may have also caused greater 
losses of applied and native sources of nitrates in NT plots via runoff and leaching (Eck and Jones, 
1992; Jones et aI., 1995). However, accumulation ofN03 --N near the soil surface in 2000 under ST 
(Fig. 3) suggests that mineralization was greater in these plots during this particularly dry growing 
season. 
70 
CONCLUSIONS 
Greater uptake of N by wheat and sorghum in conjunction with higher levels of residual 
nitrates in ST plots as compared with NT indicate mineralization of soil organic matter proceeded 
at a more rapid rate under ST. Plots receiving urea had significantly greater sorghum yields and N-
uptake than manure and compost amended plots. Sorghum grain yield response to fertilizer 
treatments was reduced under ST as compared to NT due to the higher levels of residual NO~ --N 
near the surface and possibly at greater depths. Sweep-tillage may be required to maintain higher 
mineralization rates to permit a more efficient use of manure nitrogen. However, nitrogen 
requirements under ST are not as great as compared to NT due to greater water economy with NT. 
ACKNOWLEDGMENTS 
The authors gratefully acknowledge the technical assistance of Jourdan Bell and statistical advice 
of Tom Popham. 
REFERENCES 
Eck, H.V. and O.R Jones. 1992. Soil nitrogen status as affected by tillage, crops, and crop 
sequences. Agron. J. 84:660-668. 
EPA, 1983. Methods for chemical analysis for water and wastes. EP A/6/4-79-020. US Govt. Printing 
Office, Washington, D.C. 
Jones, O.R, V.L. Hauser, and T.W. Popham. 1994. No-tillage effects on infiltration, runoff, and 
water conservation on dryland. Trans. ASAE 37:473-479. 
Jones, O.R and T.W. Popham. 1997. Cropping and tillage systems for dryland grain production in 
the Southern High Plains. Agron. J. 89:222-232. 
Jones O.R, S.J. Smith, L.M. Southwick and AN. Sharpley. 1995. Environmental impacts of dryland 
residue management systems in the southern High Plains. 1. Environ. Qual. 24:453-460. 
Keeney D.R and D.W. Nelson. 1982. Nitrogen-Inorganic forms. pp 643-698. In: AL. Page, RH. 
Miller, and D.R Keeney (Eds.) Methods of soil analysis part 2. Chemical and microbiological 
properties. 2nd Ed. Am. Soc. Agron., Madison, WI. 
Littell, Re., G.AMilliken, W.W. Stroup, RD. Wolfinger. 1996. SAS system for mixed models. 
SAS Institute Inc., Cary, NC, USA 
Smith, D.R, P.A Moore, e.L. Griffis, T.C. Daniel, D.R Edwards, and D.L. Boothe. 2001. Effects 
of alum and aluminum chloride on phosphorus runoff from swine manure. J. Environ. Qual. 30:992-
998. 
71 


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Tillage And Beef Cattle Manure Effects On Soil Nitrogen In A Dryland Rotation

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