| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Land Resource Science, University of Guelph, Guelph, ON, N1G 2W1, Canada
* Corresponding author (trashid{at}uoguelph.ca)
Received for publication August 4, 2004.
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
middle. Nitrogen fertilizer requirements for corn production in conjunction with FOG management were also affected by slope position. Essentially no additional fertilizer N was required for corn production at the lower landscape position. It was estimated that site-specific fertilizer N management on FOG-amended fields could result in an average savings of 51 and 63 kg N ha–1 (with a potential economical savings of US$42 and US$52 ha–1) during 1995 and 1996, respectively.
Abbreviations: FOG, oily food waste • MERN, maximum economic rate of nitrogen • MEY, maximum economic yield • PPNT, pre-plant time of sampling • PSNT, pre-sidedress time of sampling
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
Present N fertilizer recommendations largely ignore response differences due to soil variability at different landscape positions (Kitchen et al., 1995). Application of a single fertilizer rate to fields having a large spatial variation in soil available N can result in overfertilization in some areas and underfertilization in other areas (Malzer et al., 1996). Overfertilization of N may result in the short-term accumulation of NO3–N in soil (Roth and Fox, 1990; Vanotti and Bundy, 1994) and result in NO3–N leaching from the root zone (Meisinger and Randall, 1991; Kachanoski and Von Bertoldi, 1997) and into the ground water (Wedland et al., 1998). On the other hand, underfertilization limits yields (Pan et al., 1997) and may restrict economic returns (Scharf and Lory, 2000). Management strategies have been developed to reduce NO3–N leaching losses including growing winter cover crops (Francis et al., 1998), return of on-farm organic waste materials such as cereal straw (Nicholson et al., 1997), and application of off-farm organic waste materials like FOG (Rashid and Voroney, 2003).
On the other hand, soils under intensive continuous cultivation are in a net deficit of C and require external sources of organic matter to equilibrate their deficient C balance. With the aim of increasing the organic matter level in agricultural lands, there has been a growing interest in the advantages of using waste and organic residues in agriculture during the last decade (Martens and Frankenberger, 1992). Application of FOG to agricultural soils as a C source is one of the options. Application of FOG significantly increased the soil biomass (Plante and Voroney, 1998) and soil organic matter (Rashid and Voroney, 2004).
Nitrogen immobilization has been reported during decomposition of oil, fats, volatile fatty acids, and FOG in controlled laboratory (Smith, 1974; Higuchi and Kurihara, 1980; Kirchmann and Lundvall, 1993; Sorensen, 1998; Plante and Voroney, 1998) and field studies (Rashid and Voroney, 2003). Rashid and Voroney (2004) reported that corn grain yields were higher in plots where FOG was applied in the previous fall compared with the yields recorded from plots received FOG in spring. Higher corn grain yields in fall-applied FOG plots were probably due to remineralization of immobilized N during FOG decomposition. These results prompted us to conduct a field-scale study at a farm having rolling topography, to develop a strategy for FOG application to agricultural soils and to develop N fertilizer recommendations for corn grown on FOG-amended fields.
Although considerable research has been done during the last few years to understand the effect of site-specific N management for corn, information regarding production on waste-amended soils (such as FOG application) is not available. The main objectives of this study were to examine the variability of available N and corn grain yield at different landscape positions of FOG-amended fields and to determine whether N fertilizer management could be improved by considering the spatial variability of soil NO3–N in soil at different slope positions.
|
MATERIALS AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
|
|
|
Soil samples (a composite sample of 10 cores from each replication) from the 0- to 30-cm soil depth were taken before FOG application on 26 April. Soil samples were also taken from zero-N plots after FOG application at pre-plant time of sampling (PPNT) on 21 May and pre-sidedress time of sampling (PSNT) on 25 June at each slope position to analyze for plant available N (NO3–N). Soil samples were also taken from the adjacent areas at these sampling times at each slope position where FOG was not applied to compare with the soil available N contents of FOG-amended area. Soil samples were brought to the laboratory and kept at –8°C until prepared for analyses. Soil samples for the soil NO3–N were extracted with 2 M KCl (Keeney and Nelson, 1982) and the extract was analyzed for NO3–N by using a TRAACS 800 instrument (Bran+Luebbe, Norderstedt, Germany) (Tel and Heseltine, 1990).
At maturity two central rows (1.52 x 5 m; 7.6 m2) of each plot were hand-harvested at both experimental locations to determine the corn grain yields. At harvesting time a subsample of cobs (10) was collected for oven-drying and oven-dried cobs were shelled and corn grain yield was calculated (expressed on 155 g kg–1 moisture content basis). Corn grain yield data recorded from FOG-amended plots at different slope positions were used to calculate the MERN as proposed by McGonigle et al. (1996):
 | [1] |
Maximum economic yield (MEY) was calculated by putting MERN as N in a quadratic response equation:
 | [2] |
The analysis of variance for the effects of FOG treatment, slope position, and time of sampling on soil NO3–N contents was performed by the PROC GLM procedure of SAS (SAS Institute, 1990). The effects of landscape position and time of sampling on soil NO3–N contents within a FOG treatment and landscape position and FOG treatment within a time of sampling during a particular year were determined by contrast comparisons. The response of corn grain yield to applied fertilizer N at different slope positions in a year was analyzed by PROC MIXED procedure. Contrasts were developed to compare the individual response curve components (intercept, linear, and quadratic) and whole response curves obtained from upper, middle, and lower slope positions.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
|
The interaction between landscape positions x FOG treatment also significantly affected (P < 0.05) the soil NO3–N contents during both years. Soil NO3–N contents of FOG-amended plots were significantly lower (P < 0.05) compared with nonamended plots at all slope positions (upper, middle, and lower) at PPNT during both years. On the other hand, soil NO3–N contents of FOG-amended plots at PSNT were significantly higher compared with nonamended plots at lower slope positions but not significantly different at upper and middle slope positions during both years.
Corn Grain Yields
Experimental plots at different slope positions were only set out where FOG was applied to determine the corn grain yield response to applied nitrogen. Our major emphasis was to determine the effect of FOG application on corn grain yields and corn response to applied N at different slope positions. Therefore, the statistical analysis of the data regarding corn grain yields and corn yield response to applied N recorded at different slope positions was performed only under FOG-amended conditions.
The interactive effect of slope position x N application rate significantly affected the corn grain yields during both years. Maximum corn grain yields were obtained at the lower slope position followed by upper and middle slope positions in 1995 (Fig. 2) . Corn grain yields at each N fertilizer application rate at the upper and middle slope positions were not significantly different from each other (P < 0.05). Contrast comparisons of N response curves (intercept, linear, and quadratic components together; whole response curve) show that the corn grain yield response to applied N during 1995 was significantly different for each slope position. The increases in corn grain yield due to different fertilizer N application rates over the control at the upper and middle slope positions were 15 to 20 and 10 to 21%, respectively. The yield increases due to different N fertilizer application rates at the lower slope position were only 3 to 4%. Corn grain yields at different N application rates at the lower slope position were 22 to 42% higher compared with the upper slope position and 23 to 44% higher compared with the middle slope position in 1995.
|
Maximum Economic Rate of Nitrogen (MERN) and Maximum Economic Yield (MEY)
The highest MERNs of 105 and 110 kg ha–1 were calculated for the middle slope position followed by the upper slope position (97 and 96 kg ha–1). The MERN for the upper slope position was similar (P < 0.05) to that for the middle slope position during 1995; however, MERN for the upper slope position was significantly lower compared with the middle slope position during 1996 (Table 4). The MERN values for upper and middle slope positions were significantly higher compared with the lower slope position during both years. A small amount of supplemental N (3 and 4 kg ha–1) was required at the lower slope position during 1995 and 1996, respectively.
|
The comparison of site-specific and single-rate N fertilizer requirements during 1995 and 1996 is presented in Table 5. Nitrogen application at a single rate (85 kg N ha–1 in 1995 and 91 kg N ha–1 in 1996) resulted in overfertilization in lower slope positions (+82 and +87 kg N ha–1). On the other hand, upper (–11 and –5 kg N ha–1) and middle slope positions (–20 and –19 kg N ha–1) were underfertilized during both years. Site-specific N fertilizer management resulted in savings of 51 kg N ha–1 in 1995 and 63 kg N ha–1 in 1996 compared with single rate of N fertilizer.
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
It is interesting to note that at PSNT the soil NO3–N contents (0- to 30-cm soil depth) at different slope positions under FOG-amended plots during both years were significantly higher compared with unamended plots. Soil samples at PSNT were taken 8 wk after the FOG application and applied FOG was probably decomposed during this time. Plante (1996) reported that 50% of applied FOG was decomposed within 28 d. The increase in soil NO3–N at PSNT shows that immobilized N during FOG decomposition was probably remineralized. Rashid and Voroney (2004) in a field study conducted on a loam soil showed that soil available N immobilized due to FOG application in fall was remineralized in spring and was available to the next corn crop. Nitrogen immobilized due to FOG application in spring was not remineralized and was not available for the corn crop growth, which resulted in a significant reduction in corn grain yields. This study was conducted on a sandy soil and FOG was applied at the same rate (10 Mg ha–1). A rapid decomposition of FOG can be expected in sandy soils as the decomposition rate of organic materials is comparatively rapid in coarse-textured soils compared with fine-textured soils (Jenkinson, 1988; Ladd et al., 1990; Hassink, 1992). The relative amount of large pores is usually higher in coarse-textured soils compared with fine-textured soils (Papendick and Campbell, 1981) and changes in the pore size distribution toward a greater proportion of large pores are accompanied by higher rates of C mineralization (Franzluebbers, 1999).
Large colonies of Trichoderma sp. fungi were also observed on the surface of the soil during the crop growing season, as observed in our other experiments (Rashid and Voroney, 2004) at other locations. This observation indicates that microbial activity was enhanced due to the application of FOG to soil as a C source. Plante and Voroney (1998) conducted a laboratory study on FOG decomposition and reported a significant increase in soil respiration and soil biomass in FOG-amended soils compared with the control.
Soil available N (NO3–N) was also spatially and temporally variable and was significantly affected by the interactive effect of landscape positions and time of sampling under FOG amendments as well as control conditions. It is well established that topography is a primary factor contributing to soil variability as it influences both soil fertility and water availability (Mulla 1993). Higher values of soil available N (NO3–N) were recorded at the lower slope position compared with the upper and middle slope positions during both years. This can partly be attributed to relatively higher organic matter content (31 and 35 g kg–1) at the lower slope position compared with upper (22 and 26 g kg–1) and middle (24 and 21 g kg–1) slope positions. Total N contents were also higher (1.2 and 1.4 g kg–1) at the lower slope position compared with upper (1.1 and 1.2 g kg–1) and middle (1.1 g kg–1) slope positions. Lower slope positions typically have high amounts of organic matter and total N compared with soils in upper slope positions (Gregorich and Anderson, 1985) because they collect N-rich topsoil from surrounding slope positions as a result of redistribution (Pennock et al., 1994).
Higher soil NO3–N contents at lower slope positions during both years might have accelerated the decomposition of applied oily food waste, which resulted in remineralization of immobilized N during FOG decomposition. Amount of soil available N also affects the decomposition of applied waste materials, as N availability influences decomposition of organic materials (Recous et al., 1995; Mary et al., 1996). Recous et al. (1995) reported that rate of plant residue decomposition was higher where soil available N levels were high compared with low soil available N levels. Significantly higher corn grain yields at lower slope positions reveal that N availability and N demand of plants was well synchronized under these conditions. We observed a similar response in another experiment conducted on loamy soils. In that experiment PSNT NO3–N contents and corn grain yields were higher in plots that received FOG in fall compared with the unamended plots (Rashid and Voroney, 2004).
Current N fertilizer recommendations for conventional corn production in Ontario are based on a single rate and are determined by a PSNT soil NO3–N test. Given a wide range in fertilizer N requirements due to topography, site-specific fertilizer N management has the potential to reduce costs of corn production compared with current N management practices. Our results show that almost no N fertilizer was required for corn production in conjunction with FOG management at lower slope positions while upper and middle slope positions were underfertilized during both years. Other authors have also reported that application of a single N rate to fields having a large spatial variation in soil mineral N resulted in underfertilization in some areas and overfertilization in other areas (Malzer et al., 1996; Kachanoski and Von Bertoldi, 1997; Mamo et al., 2003). It is also worth noting that lower slope positions produced significantly higher MEY compared with upper and middle slope positions during both years with the minimal MERN (3 and 4 kg N ha–1 for 1995 and 1996, respectively).
The production of significantly higher MEY with a negligible amount of N fertilizer application at lower slope positions reveals that NO3–N conservation through recycling (in this case FOG application) can contribute toward savings in fertilizer input cost. Maximum economic rate of N values calculated for corn at different slope positions show that a negligible amount of N fertilizer or no N fertilizer was required at lower slope positions during both years. Our results show that site-specific N fertilizer recommendation saved 51 and 63 kg N ha–1 during 1995 and 1996, respectively, without any yield losses. Mamo et al. (2003) reported a uniform application recommendation of 145 kg N ha–1 for the whole field, which was half overfertilized and half underfertilized. They further reported that variable rate N applications according to economically optimum nitrogen rate (EONR) for corn saved 69 and 75 kg ha–1 compared with uniform rate during the two years of experimentation and potential economic benefits were US$8 and US$23 ha–1 higher than the uniform N rate. The savings in terms of N fertilizer input costs were US$42 and US$52 ha–1 during 1995 and 1996, respectively. By reducing fertilizer input costs in areas that are overfertilized and by increasing yields in areas of the field that are underfertilized, net returns to the producer and farm profitability could be increased by 10 to 20% (Malzer et al., 1996).
|
CONCLUSIONS |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
middle. Nitrogen fertilizer requirements for corn production in conjunction with FOG management were also affected by slope position. At lower landscape positions essentially no additional fertilizer N was required for corn production at the lower landscape position, probably due to soil N conservation through recycling during FOG decomposition. It was estimated that site-specific fertilizer N management under FOG-amended soils could result in an average savings of 57 kg N ha–1. |
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
|---|
Related articles in JEQ:
This article has been cited by other articles:
|
|
 |
|
  K.-I. Kim, D. E. Clay, C. G. Carlson, S. A. Clay, and T. Trooien Do Synergistic Relationships between Nitrogen and Water Influence the Ability of Corn to Use Nitrogen Derived from Fertilizer and Soil? Agron. J., May 7, 2008; 100(3): 551 - 556. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. Kaown, Y. Hyun, G.-O. Bae, and K.-K. Lee Factors Affecting the Spatial Pattern of Nitrate Contamination in Shallow Groundwater J. Environ. Qual., August 31, 2007; 36(5): 1479 - 1487. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. T. Rashid and R. P. Voroney Nitrogen Fertilizer Recommendations for Corn Grown on Soils Amended with Oily Food Waste J. Environ. Qual., October 12, 2005; 34(6): 2045 - 2051. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Crop Science | |||
| Vadose Zone Journal | Journal of Plant Registrations | ||||
| Journal of Natural Resources and Life Sciences Education |
Soil Science Society of America Journal |
