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- IGC Proceedings (1993-2023) (7)
- Kansas Agricultural Experiment Station Research Reports (4)
- United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications (4)
- Andrew W. Lenssen (3)
- Department of Agronomy and Horticulture: Faculty Publications (2)
Articles 1 - 27 of 27
Full-Text Articles in Life Sciences
Regeneration Of Themeda Triandra In Humid South African Rangelands, K Adams, J E. Danckwerts
Regeneration Of Themeda Triandra In Humid South African Rangelands, K Adams, J E. Danckwerts
IGC Proceedings (1993-2023)
Themeda triandra seeds were planted into undisturbed, burnt and tilled treatments in degenerate humid grassland. More seedlings emerged and survived on tilled soil than on the other two treatments. The plants on the tilled treatments were also larger (had more tillers with greater mass than the other two). The effect of tillage was attributed to removal of competition from undesirable competitors, which seems essential in the reintroduction of T. triandra into humid grasslands of South Africa.
Root Distribution Study Of Forage Gramina Under Conservation Tillage Systems, By A Tracer Technique, M B. Barrios, A Bujan, A A. Bozzo, S P. Debelis
Root Distribution Study Of Forage Gramina Under Conservation Tillage Systems, By A Tracer Technique, M B. Barrios, A Bujan, A A. Bozzo, S P. Debelis
IGC Proceedings (1993-2023)
The aim of this work is to evaluate the root activity patterns of three forage graminaceous species under different tillage systems. The field experiment was carried out during 1993-94 in a Mollisol under three tillage systems: plowing, chiseling tillage and subsoiling tillage system cultivated with Lolium multiflorum, Bromus catharticus and Phalaris aquatica. Significant differences were found in lateral root distribution between tillage systems. Subsoiling tillage system treatment showed the largest presence of roots at 10 cm lateral distance from the plants. No differences in root activity at 10, 20, and 30 cm from the plant were found in chiseling …
Corn Or Sorghum/ Italian Ryegrass Forage Rotation Under Different Cultivation Systems In High Rainfall Areas Of Spain, M Rodriquez-Juli, I Bordegarai, G Besga, A Martinez, J Pineiro
Corn Or Sorghum/ Italian Ryegrass Forage Rotation Under Different Cultivation Systems In High Rainfall Areas Of Spain, M Rodriquez-Juli, I Bordegarai, G Besga, A Martinez, J Pineiro
IGC Proceedings (1993-2023)
A field assay was established at three locations in northern Spain with the main objective of characterizing forage production and evaluating no-tillage methods as an alternative to the conventional labour practices. Three fields located in Guntìn (Galicia), Grado (Asturias) and Derio (Basque Country) were sown different rotations: Italian ryegrass (Lolium multiflorum L.)-corn (Zea mays L.) and Italian ryegrass-sorghum (Sorghum bicolor (L.) Moench x sudangrass) under two different systems: conventional tillage (T) and no-tillage (NT). Italian ryegrass-corn rotation was more productive than the sorghum x sudangrass rotation in the three sites, with average forage yield varying from 17.8 …
Soil Quality Under Permanent And Annual Pastures: Its Implications For Soil Microbial Activity And Nutrient Turnover, R. J. Haynes, R. M. Milne, N. Miles
Soil Quality Under Permanent And Annual Pastures: Its Implications For Soil Microbial Activity And Nutrient Turnover, R. J. Haynes, R. M. Milne, N. Miles
IGC Proceedings (1993-2023)
Dairy farming in humid, subtropical parts of South Africa is based on permanent kikuyu grass (Pennisetum clandestinum) swards. However, there is a shortage of feed during the winter because low temperatures limit kikuyu growth. As a result, annual pastures incorporating temperate grasses, are grown for winter feed production. The grasses used are typically annual ryegrass (Lolium multiflorum) and sometimes perennial ryegrass (Lolium perenne). Kikuyu is so invasive in the locality that it becomes dominant within a few years, even if the field is sown to perennial ryegrass. For that reason, the swards are usually …
Effects Of Tree And Tillage Systems On The Productivity Of The Herbaceous Stratum In Silvopastoral Systems In The Southwest Of Córdoba, Argentina, O. Plevich, C. Saroff, C. Cholaky, T. Pereyra, O. Barotto, H. Pagliaricci
Effects Of Tree And Tillage Systems On The Productivity Of The Herbaceous Stratum In Silvopastoral Systems In The Southwest Of Córdoba, Argentina, O. Plevich, C. Saroff, C. Cholaky, T. Pereyra, O. Barotto, H. Pagliaricci
IGC Proceedings (1993-2023)
In the southwest of Córdoba, Argentina, there are lands with severe water erosion, due to the interaction of rolling pampas, high intensity precipitation, loam soil, and farming systems based on annual crops (Cantero et al., 1998). In an attempt to mitigate the erosive processes, a silvopastoral system was established in which winter forage was combined with trees. To improve the physical condition of the soil, two tillage systems were implemented. The objective of this paper was to determine the effect of trees and tillage systems on the production of forage.
Previous Grass-Lucerne Mixtures Affect Barley Yield And Quality In A Semiarid Location Of The Canadian Prairie Region, P. G. Jefferson, F. Selles, R. P. Zentner, R. Lemke
Previous Grass-Lucerne Mixtures Affect Barley Yield And Quality In A Semiarid Location Of The Canadian Prairie Region, P. G. Jefferson, F. Selles, R. P. Zentner, R. Lemke
IGC Proceedings (1993-2023)
In the semiarid region of the Canadian prairies perennial forages are not rotated with annual crops because previous experiments reported negative impacts (Kilcher and Anderson 1963; Campbell et al. 1990). However, previous research used persistent species while short-lived species could have less adverse effect. Our objective was to compare three grass species in three lucerne mixtures terminated with tillage or herbicide for effects on barley grain, N concentration, and N uptake.
The Impact Of Tillage System For Small-Grain Pasture Establishment On The Performance Of Growing Beef Calves In Arkansas, P. Beck, S. Gunter, M. Anders, K. Lusby, D. Hubbell
The Impact Of Tillage System For Small-Grain Pasture Establishment On The Performance Of Growing Beef Calves In Arkansas, P. Beck, S. Gunter, M. Anders, K. Lusby, D. Hubbell
IGC Proceedings (1993-2023)
In the United States, governmental regulations mandate the improvement of farming practices to improve environmental quality. There is a requirement to reduce the siltation of waterways, soil carbon losses, and nutrient runoff along the Mississippi River Delta. The use of small-grain forages by grazing cattle offers real opportunities to produce high-quality forage for cattle production during the winter and spring months. No-till and reduced tillage practices developed primarily for grain production may offer environmental and economic solutions for both grain farmers and cattle producers. Producers are slow to adopt conservation tillage practices because of a perceived risk of reduced production. …
Long-Term Changes In Soil Surface Properties As Affected By Management Practices In A Wheat-Soybean, Double-Crop System, Machaela Morrison
Long-Term Changes In Soil Surface Properties As Affected By Management Practices In A Wheat-Soybean, Double-Crop System, Machaela Morrison
Crop, Soil and Environmental Sciences Undergraduate Honors Theses
Long-term agricultural sustainability and productivity are controlled by the integrative effects of different management practices on the soil. Many Arkansas producers use the double-crop system to grow soybeans [Glycine max (L.) Merr] and wheat (Triticum aestivum L.). Studying combinations of different, non-traditional, alternative agricultural techniques may help producers better understand the long-term implications of various management practice options on sustainability and productivity. The objective of this study was to evaluate the effects of agricultural management practices, including residue level, tillage, irrigation, and burning, and soil depth on the change in various soil properties from 2010 to 2020 in …
Intervention Of Climate-Smart Practices In Wheat Under Rice-Wheat Cropping System In Nepal, Janma Jaya Gairhe, Mandeep Adhikari, Deepak Ghimire, Arun Khatri-Chhetri, Dinesh Panday
Intervention Of Climate-Smart Practices In Wheat Under Rice-Wheat Cropping System In Nepal, Janma Jaya Gairhe, Mandeep Adhikari, Deepak Ghimire, Arun Khatri-Chhetri, Dinesh Panday
Department of Agronomy and Horticulture: Faculty Publications
Besides a proper agronomic management followed by Nepalese farmers, wheat (Triticum aestivum L.) production has been severely affected by changing climate. There are many interventions, including climate-smart practices, to cope with this situation and possibly enhance crop and soil productivity. Field experiments were set up in a randomized complete block design with six treatments (TRT) with four replications in three locations (LOC) during wheat-growing seasons in Nepal from 2014 to 2016. Treatments included (i) Controlled Practice (CP), (ii) Improved Low (IL), (iii) Improved High (IH), (iv) Climate Smart Agriculture Low (CSAL), (v) Climate Smart Agriculture Medium (CSAM), and (vi) …
Soil Health Assessment For The Agroecosystems Of West Tennessee, Surendra Singh
Soil Health Assessment For The Agroecosystems Of West Tennessee, Surendra Singh
Doctoral Dissertations
Soil health assessment is important for making informed sustainable management decisions in production systems. An established standardized method to quantify soil health is lacking and the validity of the existing methods across agroecoregions and cropping systems is not yet proven. Therefore, this study aims to evaluate the feasibility of widely discussed three soil health tests - Haney’s Soil Health Test (HSHT), Comprehensive Assessment of Soil Health (CASH), and Alabama Soil Health Index (ASHI) to assess soil health in diverse cropping systems of Tennessee. Since these approaches were originally developed for specific agroecoregions, we hypothesized that these tests are not sensitive …
Nematode Populations As Affected By Residue And Water Management In A Long-Term Wheat-Soybean Double Crop In Eastern Arkansas, Lucia Emperatriz Escalante Ortiz
Nematode Populations As Affected By Residue And Water Management In A Long-Term Wheat-Soybean Double Crop In Eastern Arkansas, Lucia Emperatriz Escalante Ortiz
Graduate Theses and Dissertations
Soybeans (Glycine max) are one of the major row crops in the United States, particularly in Arkansas. Soybean cyst nematode (SCN, Heterodera glycines) and southern root-knot nematode (RKN, Meloidogyne incognita) are two of the most damaging pests that cause major economic losses in soybeans. Little is known concerning the effects of common and alternative agronomic practices on nematodes in fields with nematode population densities below threshold levels. Therefore, the objective of this study was to evaluate the effects of the combination of tillage (conventional tillage and no-tillage), irrigation (irrigated and non-irrigated), wheat (Triticum aestivum) residue burning (burned and no burned), …
Long-Term Tillage Impact On Soil Hydraulic Properties, Humberto Blanco-Canqui, Brian J. Weinhold, Virginia L. Jin, Marty R. Schmer, Leonard C. Kibet
Long-Term Tillage Impact On Soil Hydraulic Properties, Humberto Blanco-Canqui, Brian J. Weinhold, Virginia L. Jin, Marty R. Schmer, Leonard C. Kibet
Department of Agronomy and Horticulture: Faculty Publications
An improved understanding of the impact of tillage systems on soil hydraulic properties is necessary to conserve and manage soil water under a changing climate. The objective of this study was to specifically measure soil hydraulic properties (total porosity, water infiltration, saturated hydraulic conductivity, and water retention characteristics) in no-till, chisel plow, disk, and moldboard plow systems under rainfed continuous corn (Zea mays L.) after 35 yr on silty clay loam soils in eastern Nebraska. We measured ponded water infiltration (positive soil water pressure) and tension (-1 kPa matric potential) infiltration to exclude macropore (>125 mm diameter) flow. …
Contrasting Soil Management Practice, Nitrogen Source, And Harvest Method Effects On Corn Production In Ohio And Tennessee, Casey Theresa Sullivan
Contrasting Soil Management Practice, Nitrogen Source, And Harvest Method Effects On Corn Production In Ohio And Tennessee, Casey Theresa Sullivan
Masters Theses
Current global agricultural production is completed with little regards to sustainable soil use. It is clear that the research and use of sustainable management practices must be expanded in order to preserve this natural resource. The objectives of this research were to focus on improving soil fertility and resource use efficiency by 1) evaluating farm management practices to find those that conserve soil and improve yields, 2) looking at alternative methods of fertilizing through the reuse of waste materials in agriculture. The last objective was to 3) test a more efficient method data collection and research production, resulting in more …
Evaluation Of Tillage, Crop Rotation, And Cover Crop Impacts On Corn Nitrogen Requirements In Southeastern South Dakota, Sara Louise Berg
Evaluation Of Tillage, Crop Rotation, And Cover Crop Impacts On Corn Nitrogen Requirements In Southeastern South Dakota, Sara Louise Berg
Electronic Theses and Dissertations
Nitrogen (N) is a vital factor of corn (Zea mays) production. Previous work in South Dakota has shown that there is uncertainty as to whether nitrogen requirements are the same for corn raised under no-till (NT) versus conventional till (CT) production systems. The objective of this study was to evaluate whether N requirements continue to be greater under long-term NT versus CT production systems in southeastern South Dakota, while also considering effects from cover crops and crop rotation. This was a two year study conducted at the SDSU Southeast Research Farm near Beresford, SD; it was superimposed on a long-term …
Response Of Soybean Grown On A Claypan Soil In Southeastern Kansas To The Residual Of Different Plant Nutrient Sources And Tillage, D. W. Sweeney, P. Barnes, G. Pierzynski
Response Of Soybean Grown On A Claypan Soil In Southeastern Kansas To The Residual Of Different Plant Nutrient Sources And Tillage, D. W. Sweeney, P. Barnes, G. Pierzynski
Kansas Agricultural Experiment Station Research Reports
The residual effects of turkey litter and fertilizer amendments applied in previous years had little effect on the yield, yield components, and dry matter production of the following soybean crop grown in 2014.
Tillage And Nitrogen Placement Effects On Yields In A Short-Season Corn/Wheat/Double-Crop Soybean Rotation, D. W. Sweeney
Tillage And Nitrogen Placement Effects On Yields In A Short-Season Corn/Wheat/Double-Crop Soybean Rotation, D. W. Sweeney
Kansas Agricultural Experiment Station Research Reports
In 2013, late planting resulted in corn yields that were less than 100 bu/a. Nitrogen (N) placement did not affect yields in the higher-yielding conventional tillage system, but knifing tended to result in greater yield in reduced and no-till systems.
Fertilizer Placement And Tillage Interaction In Corn And Soybean Production, A. T. Rosa, D. A. Ruiz Diaz
Fertilizer Placement And Tillage Interaction In Corn And Soybean Production, A. T. Rosa, D. A. Ruiz Diaz
Kansas Agricultural Experiment Station Research Reports
Different tillage systems can affect the availability of phosphorus (P) by changing the soil environment. The objective of this study was to evaluate the effects and interaction of fertilizer placement, tillage, and varieties for soybean and corn. The experiment was established at two locations in Kansas in 2014. The experimental design was a factorial in a randomized complete block with four replications. Three fertilizer treatments were combined with two tillage systems and two varieties of soybean and corn selected based on contrasting root systems. Plant tissue samples were collected during the vegetative and reproductive stages to evaluate P concentration, P …
Tillage And Nitrogen Placement Effects On Yields In A Short-Season Corn/Wheat/Double-Crop Soybean Rotation, D. W. Sweeney
Tillage And Nitrogen Placement Effects On Yields In A Short-Season Corn/Wheat/Double-Crop Soybean Rotation, D. W. Sweeney
Kansas Agricultural Experiment Station Research Reports
Overall in 2014, adding nitrogen (N) improved average wheat yields, but different N placement methods resulted in similar yields. Double-crop soybean yields were unaffected by tillage or the residual from N treatments that were applied to the previous wheat crop.
Long-Term Effects Of Rice Rotation, Tillage, And Fertility On Near-Surface Soil Carbon And Nitrogen Cycling, Jill Marie Motschenbacher
Long-Term Effects Of Rice Rotation, Tillage, And Fertility On Near-Surface Soil Carbon And Nitrogen Cycling, Jill Marie Motschenbacher
Graduate Theses and Dissertations
Rice (Oryza sativa L.)-based cropping systems are different from other row crops due to the flood-irrigation scheme used from about one month after planting to a few weeks prior to harvest. The frequent cycling between anaerobic (i.e., flooding during the growing season) and aerobic (i.e., generally, the remainder of the year) conditions can influence the rate of soil organic matter (SOM) decomposition, which can greatly influence carbon (C) and nitrogen (N) storage and sequestration in the soil over time. Therefore, a study was conducted on a silt-loam soil (fine, smectitic, thermic, Typic Albaqualf) at the Rice Research and Extension Center …
Tillage And Cropping Sequence Impacts On Nitrogen Cycling In Dryland Farming In Eastern Montana, Usa, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg
Tillage And Cropping Sequence Impacts On Nitrogen Cycling In Dryland Farming In Eastern Montana, Usa, Upendra M. Sainju, Thecan Caesar-Tonthat, Andrew W. Lenssen, Robert G. Evans, Robert Kolberg
Andrew W. Lenssen
Information on N cycling in dryland crops and soils as influenced by long-term tillage and cropping sequence is needed to quantify soil N sequestration, mineralization, and N balance to reduce N fertilization rate and N losses through soil processes. The 21-yr effects of the combinations of tillage and cropping sequences was evaluated on dryland crop grain and biomass (stems + leaves) N, soil surface residue N, soil N fractions, and N balance at the 0–20 cm depth in Dooley sandy loam (fine-loamy, mixed, frigid, Typic Argiboroll) in eastern Montana, USA. Treatments were no-tilled continuous spring wheat (Triticum aestivum L.) (NTCW), …
Water And Bromide Recovery In Wick And Pan Lysimeters Under Conventional And Zero Tillage, John P. Schmidt, Henry Lin
Water And Bromide Recovery In Wick And Pan Lysimeters Under Conventional And Zero Tillage, John P. Schmidt, Henry Lin
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Quantifying in situ solute transport through soils and the landscape has been widely acknowledged as important and yet challenging. The objective of this study was to evaluate water and bromide movement in no-tilled (NT) and conventionally tilled (CT) corn using two different types of in situ lysimeters—pan and capillary wick— for single rainfall events. Four zero-tension pan and four capillary-wick lysimeters were installed 1.2 m deep on opposite sides of four soil pits. Two were under NT corn, and two were under CT corn. Bromide (Br) was either surface applied or applied with an initial 25 to 27 mm of …
Tillage Effects On Soil Quality Indicators And Nematode Abundance In Loessial Soil Under Long- Term No-Till Production, R. B. Mendoza, T. G. Franti, John W. Doran, Thomas O. Powers, C. W. Zanner
Tillage Effects On Soil Quality Indicators And Nematode Abundance In Loessial Soil Under Long- Term No-Till Production, R. B. Mendoza, T. G. Franti, John W. Doran, Thomas O. Powers, C. W. Zanner
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Soil quality indicators and nematode abundance were characterized in a loessial soil under long-term conservation tillage to evaluate the effects of no-till, double-disk, chisel, and moldboard plow treatments. Indicators included soil electrical conductivity (EC), soil texture, soil organic matter (SOM), and total particulate organic matter (tPOM). Nematode abundance was positively correlated with EC, silt content, and total POM and negatively correlated with clay content. Clay content was the main source of variation among soil quality indicators and was negatively correlated with nematode abundance and most indicators. The gain in SOM in the no-till system amounted to 10887 kg over the …
Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Dryland Plant Biomass And Soil Carbon And Nitrogen Fractions On Transient Land As Influenced By Tillage And Crop Rotation, Andrew W. Lenssen, Upendra M. Sainju, Thecan Caesar-Thonthat, Jed Waddell
Andrew W. Lenssen
Soil and crop management practices may alter the quantity, quality, and placement of plant residues that influence soil C and N fractions. We examined the effects of two tillage practices [conventional till (CT) and no-till (NT)] and five crop rotations [continuous spring wheat (Triticum aestivum L.) (CW), spring wheat–fallow (W–F), spring wheat–lentil (Lens culinaris Medic.) (W–L), spring wheat–spring wheat–fallow (W–W–F), and spring wheat–pea (Pisum sativum L.)–fallow (W–P–F)] on transient land previously under 10 years of Conservation Reserve Program (CRP) planting on the amount of plant biomass (stems + leaves) returned to the soil from 1998 to 2003 and soil C …
Incorporating Sheep Into Dryland Grain Production Systems I. Impact On Over-Wintering Larva Populations Of Wheat Stem Sawfly, Cephus Cinctus Norton (Hymenoptera: Cephidae), P. G. Hatfield, Sue L. Blodgett, T. M. Spezzano, H. B. Goosey, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Incorporating Sheep Into Dryland Grain Production Systems I. Impact On Over-Wintering Larva Populations Of Wheat Stem Sawfly, Cephus Cinctus Norton (Hymenoptera: Cephidae), P. G. Hatfield, Sue L. Blodgett, T. M. Spezzano, H. B. Goosey, Andrew W. Lenssen, R. W. Kott, C. B. Marlow
Andrew W. Lenssen
Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae) is the most damaging insect pest to Montana’s $1 billion dollar per year grain industry. Current WSS control methods are either expensive, reduce wheat yields, or are not effective. Our objective was to compare burning, grazing, tilling, trampling and clipping wheat stubble fields on over-wintering WSS larval populations. Treatments were evaluated in three experiments using a randomized complete block design and four replications at each site. Eight, six, and two sites were used for Experiments 1, 2, and 3, respectively. Contrast statements were used to make pre-planned comparisons among treatments. For …
Effects Of Burial And Soil Condition On Postharvest Mortality Of Boll Weevils (Coleoptera: Curculionidae) In Fallen Cotton Fruit, S. M. Greenberg, A. T. Showler, T. W. Sappington, J. M. Bradford
Effects Of Burial And Soil Condition On Postharvest Mortality Of Boll Weevils (Coleoptera: Curculionidae) In Fallen Cotton Fruit, S. M. Greenberg, A. T. Showler, T. W. Sappington, J. M. Bradford
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
Effects of soil condition and burial on boll weevil, Anthonomus grandis grandis Boheman, mortality in fallen cotton, Gossypium hirsutum L., fruit were assessed in this study. During hot weather immediately after summer harvest operations in the Lower Rio Grande Valley of Texas, burial of infested fruit in conventionally tilled field plots permitted significantly greater survival of weevils than in no-tillage plots. Burial of infested squares protected developing weevils from heat and desiccation that cause high mortality on the soil surface during and after harvest in midsummer and late summer. A laboratory assay showed that burial of infested squares resulted in …
The Wheat Book : Principles And Practice, W K. Anderson, J R. Garlinge
The Wheat Book : Principles And Practice, W K. Anderson, J R. Garlinge
Bulletins 4000 -
Contents : Environment / revised by J. Cramb, J. Courtney and P. Tille - The structure and development of the cereal plant / revised by T.L. Setter and G. Carlton - Germination, vegetative and reproductive growth / revised by T.L. Setter and G. Carlton - Crop water use / D. Tennant - Nutrition / revised by M.D.A. Bolland, R.F. Brennan, J.W. Bowden, M.G. Mason, N.K. Edwards, M.M. Riley and S.W. Gartrell - Wheat in farming systems / revised by B. Bowden, P. Blackwell, P. Carmody, M. Ewing, R. Kingwell, R. L ghman, I. McFarlane, P. Michael, P. Nelson, I. Pritchard, …
Uptake Of Nitrogen From Soil, Fertilizer, And Crop Residues By No-Till Corn And Soybean, J. F. Power, John W. Doran, Wallace Wilhelm
Uptake Of Nitrogen From Soil, Fertilizer, And Crop Residues By No-Till Corn And Soybean, J. F. Power, John W. Doran, Wallace Wilhelm
United States Department of Agriculture-Agricultural Research Service / University of Nebraska-Lincoln: Faculty Publications
The relative availability of nitrogen (N) from indigenous soil organic N, immobilized fertilizer N, currently applied fertilizer N, and crop residues is largely unknown. A non-irrigated experiment was conducted on a silty clay loam at Lincoln, NE, with both continuous soybean [Glycine max (L.) Merr.] and corn (Zea mays L.), in which crops were produced with no tillage after surface application of 0, 0.5,1.0, or 1.5 times the quantity of aboveground crop residue produced the previous year. In 1980 and 1981, depleted 15N NH4NO3 (at 45 kg N ha-1) and crop residues …