Field-level comparison of nitrogen rates and application methods on maize yield,grain quality and nitrogen use efficiency in a humid environment

Appropriate nitrogen (N) management practices are of critical importance in improving N use efficiency (NUE), maize (Zea mays) yield and environmental quality. A six-year (2005–2010) on-farm trial was conducted in Ottawa, Canada to assess the effects of N rates and application methods on grain yield and NUE. In four out of the six-year study, grain yield increased by 60–77 kg ha^?1 by sidedress, compared to 49–66 kg ha^?1 for each kg N ha^?1 applied at preplant. Grain yield response to N between the two strategies was similar in the other growing seasons. Sidedress strategy required 15 kg N ha^?1 less of the maximum economic rate of N (MERN) than preplant application. Our results indicate that sidedress application of 90–120 kg N ha^?1 with a starter of 30 kg N ha^?1 resulted in greater yield, grain quality and NUE than preplant N application in this cool, humid and short growing-season region.     

Early interspecific dynamics,dry matter production and nitrogen use in Kernza (Thinopyrum intermedium) – alfalfa (Medicago sativa L.) mixed intercropping

ABSTRACT

The global interest in growing perennial grain crops such as intermediate wheatgrass (Thinopyrum intermedium) (Kernza) for production of food and feed is increasing. Intercropping Kernza with legumes may be a sustainable way of supplying nitrogen to soil and associated intercrop. We determined the competitive interactions between intercropped Kernza (K) and alfalfa (Medicago sativa L.) (A) under three inorganic nitrogen (N) rates N0, N1, N2 (0, 200, 400 kg ha^?1) and five species relative frequencies (SRF) (100%K:0%A, 75%K:25%A, 50%K:50%A, 25%K:75%A and 0% K:100%A) in mixed intercrops (MI) in a greenhouse pot experiment. After 11 weeks of growth. Kernza dry matter yield (DM) and N accumulated (NACC) were low, but alfalfa DM and NACC high at 0 kg N ha^?1. 200 and 400 kg N ha^?1 fertiliser application increased the competitive ability (CA) of Kernza and reduced the CA of alfalfa. SRF had large impacts on alfalfa DM, NACC and NFIX only at 0 kg N ha^?1 fertiliser, and insignificant impacts on Kernza at all N fertiliser levels, indicating that adjustment of SRF may not be an effective way to modulate the interspecific competition of Kernza. Further research on the other factors that influence the interspecific competition are warranted.     

YIELD AND YIELD COMPONENTS OF HYBRID RICE AS INFLUENCED BY NITROGEN FERTILIZATION AT DIFFERENT ECO-SITES

Hybrid rice (Oryza sativa L.) cultivars play an important role in rice production due to its high yield potential. Optimum nitrogen (N) rate is necessary to achieve the maximum yield of hybrid. The main objective of this study was to reveal the responses of yield and yield component of hybrid rice ‘Eryou 107’ to different N rates in Nanjing and Taoyuan, a special eco-site. Leaf area index (LAI), dry matter accumulation was also compared. Rice yield showed a quadratic response to N rates at both sites with maximum yields approximately 10 t ha^?1 at the 195 kg ha^?1 N rate in Nanjing and maximum yield above 18 t ha^?1 at the 375 kg ha^?1 N rate in Taoyuan. Panicle per m² was positively linear related to N rate at both sites in both years, while spikelets per panicle showed a quadratic relation. Larger sink size was the primary contributor to higher yields in Taoyuan compared with Nanjing, and panicle per m² was the main cause. With the increasing N rate, LAI increased linearly and the dry matter accumulation first increased than declined at both sites. Greater effects of N rates on yield and yield components, LAI, and biomass was observed in Taoyuan than Nanjing. Higher LAI, biomass, and larger sink size resulted in the higher yields and more N rate for maximum yields in Taoyuan, compared with Nanjing.     

Response of irrigated fodder oats to nitrogen fertilization as influenced by tillage

Irrigated green forage production under reduced tillage is thwarted by the failure to obtain adequate N fertilization. Forage accumulation, yield and nitrogen response in relation to tillage and N application were studied for two years during 1980–1982. Forage accumulation, plant height and final forage yield were significantly affected under minimum tillage (T₁). However, plant growth and green and dry forage yields were comparable under reduced (T₂) and conventional (T₃) tillage. Reduction in yield under T₁ was associated with restricted root growth and high soil strength and bulk density in the surface and subsurface layers. The optimum dose of N for T₁, T₂ and T₃ was calculated to be 107, 120 and 113 kg N ha^?1 and the estimated dry matter yield for these rates of N under each of the three tillage systems was 6.6, 9.1 and 9.5 t ha^?1, respectively. The interaction between different tillage systems and N application rates for green and dry matter production was not significant.     

Nitrogen application in direct wet-seeded rice under alternate wetting and drying irrigation condition: Effects on grain yield,dry matter production,nitrogen uptake and nitrogen use efficiencies

Yield, dry matter production, nitrogen (N) uptake and nitrogen use efficiency (NUE) of Bangladesh Rice Research Institute (BRRI) dhan29 were investigated during two consecutive dry (Boro) seasons of 2009–10 and 2010–11. The experiments were set up in a randomized complete block design with three replication having six nitrogen (N) levels of 0, 40, 80 120, 160 and 200 kg ha^?1. Nitrogen fertilization increased yield characters, dry matter production and N uptake. The economic optimum rate of N was 166 and 155 kg ha^–1 in first and second year, respectively, with corresponding yield of 7.1 and 6.5 t ha^?1. NUEs were higher in the first year, decreased with increasing N rates in most cases. Gross return over fertilizer reached the highest Tk 692 in 2009–10 and Tk 489 in 2010–11 with 160 kg N ha^–1. The results suggest that BRRI dhan29 should receive an average of 160 kg N ha^?1 for economic optimum yield.     

Use of blue-green algae and bryophyte biomass as a source of nitrogen for oil-seed rape

Summary Blue-green algal (Nostoc muscorum) or bryophyte (Barbula recurvirostra) growth on the surface of a brown earth silt loam contained in flooded columns significantly increased soil C (+20.9% and ±23.0%, respectively) and soil N (+25.1% and +9.6%, respectively) after 5 weeks in the surface 0.7-cm soil layer. Differences in the lower layers were not significant since there was no movement of C or N metabolites down the profile, even after 21 weeks. The input of C by the inoculated blue-green algae was estimated at 0.48 Mg C 100^-1 g soil or 0.45g C ha^-1; the bryophyte growth gave 0.5 Mg C ha^-1. N fixation by the blue-green algae alone was estimated at 60 kg N ha^-1 after 5 weeks of growth. Blue-green algae associated with bryophyte growth had fixed 23 kg N ha^-1 after 5 weeks, rising to 40 kg ha^-1 after 21 weeks. Decomposition of the bryophyte biomass led to a significant increase in the dry weight (+16.8%) and the N uptake (+27.5%) of spring oil-seed rape planted in homogenised soil. In contrast, soil incorporation of the blue-green algal biomass had no significant effect on yield. The equivalent mineralized N from the blue-green algal and bryophyte incorporation was estimated as 24 and 58 kg N ha^-1, respectively.     

Yield,Petiole Nitrate,and Node Development Responses of Cotton to Early Season Nitrogen Fertilization

Abstract

Nitrogen (N) fertilization continues to be of primary importance in the economically successful production of cotton (Gossypium hirsutum L.). Profit margins of producers might be expanded by increasing the uptake efficiency of applied N. Recently, N fertilization of crops grown in the Mississippi River Delta has been suspected to impact water quality in the Gulf of Mexico. Improving efficiency of N uptake could alleviate some environmental concerns by increasing the retention of N at the site of application. The objective of this study was to determine the impact of replacing preplant N applications with postemergent N applications on the growth and yield characteristics of cotton. Delayed applications of the recommended rate of N fertilizer (112 kg N ha^?1) were tested for four years under irrigated and dry land production conditions. The N rate was applied either preplant, after crop emergence, or at first square. Further, 112 kg N ha^?1 was split applied evenly at preplant + first square, and after emergence + first square. The five 112 kg ha^?1 N treatments were compared to an unfertilized control. Yield tended to be maximized with N treatments that included a first square application. Yields were usually lowest in the unfertilized control and the 112 kg N ha^?1 preplant treatments. Not surprisingly, both yield and plant growth was influenced more by irrigation than N fertilization. Years when drought conditions caused water stress and limited plant growth, dry land cotton had only limited response to the N fertilization treatments. Irrigated cotton responded to N treatments all years with increased growth and yield. Optimizing agronomic considerations, the best N fertilization timing was an after emergence + first square split application.

     

Yield and yield components of two irrigated red bean cultivars and some soil properties as influenced by wheat residues and nitrogen management

Crop residues are beneficial substances affecting crop production and soil properties. A field experiment was carried out to evaluate the effects of wheat (Triticum aestivum L.) residue rates (0, 25, 50 and 75%) combined with N levels (0, 34.5, 69, 103.5 kg ha^?1) on yield and yield components of two red common bean (Phaseolus vulgaris L.) cultivars and to monitor chemical soil parameters. The experiment was conducted at Research Center, College of Agriculture, Shiraz University, Shiraz, Iran for two years (2008–2009). The experiment was conducted as a split–split plot arranged in a randomized complete blocks design with three replications. The highest seed yield was obtained when 25–50% of residues were incorporated. The highest seed yield, seed weight per plant, 100-seed weight and seed number per pod were obtained with 103.5 kg N ha^?1 with no significant difference to 69 kg N ha^?1. Residue incorporation significantly increased soil organic carbon (SOC) as well as available K and P content. It is possible to sow red common bean as a double cropping by soil incorporation of 25–50% wheat residues with application of 69 kg N ha^?1.     

Boron fertilization improves seed yield and harvest index of Camelina sativa L. by affecting source-sink

The impact of soil (1, 2 kg ha^?1) and foliar (100, 200 mg L^?1) boron (B) with control (no B) was evaluated on phenology and yield formation of Camelina each applied at stem elongation and flowering stages. Foliar (200 mg L^?1) or soil B (2 kg ha^?1) resulted in earlier flowering and maturity, increased fruit bearing branches (19.68%), number of siliqua, seeds per siliqua (4.6%), biological yield (15%), seed yield (24%), harvest index (11.4%) and oil contents (23%) than no B. Increased fruit bearing branches, seed filled siliqua or seed numbers, harvest index and oil quality can be attributed to changes in dry matter accumulated of stem with simultaneous increase in siliqua dry weight with foliar or soil applied B. In crux, foliar (200 mg L^?1) or soil applied (2 kg ha^?1) B seems promising to improve seed and oil yield, harvest index of Camelina sativa under B deficient condition.     

Rice plant growth and nitrogen accumulation from a midseason application 1

Nitrogen (N) fertilization in rice (Oryza sativa L.) is extensive throughout the world, but fertilizer N recovery is generally low. Split fertilizer applications that coincide with plant demand have been suggested as a method of improving fertilizer N efficiency. However, the effectiveness of split applications has not been established. Furthermore, there is little information available on plant N accumulation after a midseason application. The purpose of this study was to measure plant dry matter, root growth, and N accumulation after a midseason N application and to determine the length of time during which midseason N is accumulated by the plant. ‘Cypress’ rice was drill‐seeded in a Crowley silt loam soil (fine, montmorillonitic, thermic Typic Albaqualf) and urea‐N was broadcast at 101 kg N ha^‐1 preflood. Microplots enclosed by retainers were established prior to panicle initiation (PI), and ^l5N‐labeled urea was topdressed at PI into the floodwater within each microplot at 67 kg N ha^‐1. Microplots were harvested at 1 day after topdress (DAT), 3 DAT.7DAT, 14 DAT, and at 90% heading (35 DAT). Dry matter production was not affected by the midseason N application and increased linearly from the time of midseason application until 90% heading. Root growth at the time of the midseason application was extensive and roots could be seen at the soil surface. Root length density was greatest in the top 7.5 cm of the soil profile and decreased with depth. Most accumulation of midseason N occurred within 7 DAT. Both midseason N and native N in the plant increased during this period. About half of the midseason N was accumulated by the crop, probably because of the extent of the root system. This approximates N recovery from preplant or preflood N applications. Nitrogen loss was probably due to ammonia (NH₃) volatilization. Nitrogen accumulation by the plants continued throughout the duration of the experiment. This study shows that N broadcast into the floodwater at PI is quickly and efficiently utilized.     

Yield and protein content of barley as affected by release rate of coated urea and rate of nitrogen application

Coated urea consists of a urea core and a polymer coating. It meters out urea over a period of time. In the market place, price is favorable for high protein content feed barley. The objectives of this study were to determine release rate of urea from coated urea products and relative effectiveness of urea, coated urea or a mixture of coated urea products with different release rates in increasing yield and protein content of barley. Release rate of coated urea Mini I (quick release) and Mini II (slow release) in water was determined at 23°C by recovering ten pre‐weighed granules from 500 mL water at 6 h, 2, 4, 6, 8, 10, and 12 days. The recovered granules were dried and then weighed. Barley (Hordium vulgare L. cv. Duke) was grown in potted soil (2 L) at 15°C for 90 days in a growth chamber with treatments of Nil, non‐coated urea, Mini I, Mini II, Mixture I (1/3 urea+1/3 Mini I+1/3 Mini II) and Mixture II (1/5 urea+2/ 5 Mini I+2/5 Mini II). The nitrogen (N) application rates were 100, 200 and 300 kg N ha^‐1. Above‐ground plant samples were taken at 22, 44, 66, and 90 (maturity) days after seeding, and dry matter mass per pot and N content of the plant samples were determined. The release of urea from Mini I and Mini II followed a lognomial pattern. Increasing N application rate increased dry matter yield of barley. Dry matter yield from urea tended to be higher than other treatments at each rate of N application, but that did not couple with high grain protein content. At 100 kg N ha^‐1, there was no post anthesis N assimilation (PANA) for urea and Mini I, but there were 4, 14, and 13% PANA for Mini II, Mixture I, and Mixture II, respectively. However, when N application rate was increased to 200 and 300 kg N ha^‐1, there was PANA even for urea treatment. Protein content of barley grain was higher with coated urea or mixture treatments than with urea at each rate of N application. The potential N loss (i.e., difference between percentN released from fertilizers and percent fertilizer N recovered by barley) was Mini II<Mini I<Mixture II<Mixture I for the same N application rate, and was 100<200<300 kg N ha^‐1 for the same fertilizer treatment. In conclusion, at a limited N application rate, coated urea with a slow release rate or a combination of two coated urea products (quick and slow release) with urea increased grain protein content of barley. The potential N loss was less with coated urea applied alone than with a mixture of coated urea and urea.     

Grain yield,growth response,and water use efficiency of direct wet-seeded rice as affected by nitrogen rates under alternate wetting and drying irrigation system

ABSTRACT

The present investigation aimed to determine the effectiveness of different nitrogen (N) rates on grain yield, growth, and water use efficiencies of direct wet-seeded rice and to create a relationship of N rates with growth parameters and dry matter production at different stages. The experiments compared six rates of nitrogen (0, 40,80,120,160, and 200 kg ha^–1N) replicated thrice in randomized complete block design in two conjunctive years of 2009–2010 and 2010–2011 at Bangladesh Rice Research Institute farm, Gazipur.The highest grain yield of 7.85 and 7.22 t ha^?1 was observed in N₂₀₀ treatment in 2009–2010 and 2010–2011, respectively. The relationship (R²) of total dry matter with leaf area index , leaf area duration, and crop growth rate indicated strong association during booting stage to achieved maximum dry matter during harvest. Water use efficiency varied 87–91% in different N levels.     

Yields of wheat and soil carbon and nitrogen contents following long-term incorporation of barley straw and ryegrass catch crops

Abstract. Three successive crops of winter wheat were grown on a sandy loam to test the residual effect of long‐term annual incorporation of spring barley straw at rates of 0, 4, 8 and 12 t ha^?1, and ryegrass catch crops with or without additions of pig slurry. Soil receiving 4, 8 and 12 t ha^?1 of straw annually for 18 years contained 12, 21 and 30% more carbon (C), respectively, than soil with straw removal, and soil C and nitrogen (N) contents increased linearly with straw rate. The soil retained 14% of the straw C and 37% of the straw N. Ryegrass catch‐cropping for 10 years also increased soil C and N concentrations, whereas the effect of pig slurry was insignificant. Grain yield in the first wheat crop showed an average dry matter (DM) increase of 0.7 t ha^?1 after treatment with 8 and 12 t straw ha^?1. In the two subsequent wheat crops, grain yield increased by 0.2–0.3 t DM ha^?1 after 8 and 12 t straw ha^?1. No grain yield increases were found after 4 t straw ha^?1 in any of the three years. Previous ryegrass catch crops increased yields of wheat grain, but effects in the third wheat crop were significant only where ryegrass had been combined with pig slurry. Straw incorporation increased the N offtake in the first wheat crop. In the second crop, only 8 and 12 t straw ha^?1 improved wheat N offtake, while the N offtake in the third wheat crop was unaffected. Ryegrass catch crops increased N offtake in the first and second wheat crop. Again, a positive effect in the third crop was seen only when ryegrass was combined with slurry. Long‐term, annual incorporation of straw and ryegrass catch crops provided a clear and relatively persistent increase in soil organic matter levels, whereas the positive effects on the yield of subsequent wheat crops were modest and transient.     

Nitrogen use Rationalization and Boosting Wheat Productivity by Applying Packages ‎of Humic,Amino Acids,and Microorganisms

ABSTRACT

Integrated management of soil organic matter and nutritional status of crop plants is essential to sustain the production of organic farming systems. Thus, a 2–year field experiment was conducted to examine the effects of soil additions (192 kg N ha^–1, humic+192 kg N ha^–1, humic+144 kg N ha^–1 and humic+96 kg N ha^–1) and foliar applications (amino acids, Azotobacter+yeast, and amino acids plus Azotobacter+yeast) as various fertilizer resources on growth and yield of wheat. Results showed that humic+192 kg N ha^–1 × amino acids plus Azotobacter+yeast were the effective combination for producing the highest values of flag leaf area, total dry weight, tiller number m^–2, spike weight m^–2, and grain yield ha^–1. Under foliar application of amino acids plus Azotobacter+yeast, reducing N supply from recommended rate (192 kg N ha^–1) to 144 kg N ha^–1+ humic achieved higher values of all yield traits, with a saving of 25% of applied mineral nitrogen as well as enhancing nitrogen use efficiency.     

Residual nitrogen effects on wheat following legumes in the southern plains

Increasing nitrogen (N) fertilizer prices give rise to the question of N benefits from legumes in cropping systems in the Southern Great Plains. This study quantified wheat (Triticum aestivium L.) hay production and N uptake over seven years following six years of alfalfa (Medicago sativa L.), cicer milkvetch (Astragalus cicer L.), or grass (Old World bluestem, Bothriochloa ischaemum L.) production in western Oklahoma. Precipitation over the seven years averaged 550 mm·yr^‐1. The major residual N effects were measured within the first five years. On a fine sandy loam soil, wheat hay yields averaged 3,070 kg·ha^‐1·yr^‐1 over five years following alfalfa, 2,580 kg·ha^‐1·yr^‐1 following milkvetch, and 950 kg·ha^‐1·yr^‐1 following grass with N uptake attributed to the residual effect from legumes (calculated by the difference method) averaged 34 kg N ha^‐1·yr^‐1 from alfalfa and 25 kg·ha^‐1·yr^‐1 from milkvetch. On a deep loamy sand soil, wheat hay yields averaged 1,290 kg·ha^‐1·yr^‐1 over five years following alfalfa and 710 kg·ha^‐1·yr^‐1 following grass with N uptake attributed to the residual effect from alfalfa averaged 8 kg N ha^‐1·yr^‐1. Thus, the residual N effect attributed to legumes was substantial on the fine sandy loam soil and relatively small on the deep loamy sand soil.     

Seasonal soil nitrogen dynamics affect yields of lowland rice in the savanna zone of West Africa

Background : Rice production in low‐input systems of West Africa relies largely on nitrogen supply from the soil. Especially in the dry savanna agro‐ecological zone, soil organic N is mineralized during the transition period between the dry and the wet seasons. In addition, in the inland valley landscape, soil N that is mineralized on slopes may be translocated as nitrate into the lowlands. There, both in‐situ mineralized as well as the laterally translocated nitrate‐N will be exposed to anaerobic conditions and is thus prone to losses. Aim : We determined the dynamics of soil NO₃‐N along a valley toposequence during the dry‐to‐wet season transition period and the effects of soil N‐conserving production strategies on the grain yield of rainfed lowland rice grown during the subsequent wet season. Methods : Field experiments in Dano (Burkina Faso) assessed during two consecutive years the temporal dynamics and spatial fluxes of soil nitrate along a toposequence. We applied sequential and depth‐stratified soil nitrate analysis and nitrate absorption in ion exchange resin capsules in lowlands that were open to subsurface interflow and in those where the interflow from the was intercepted. During one year only we also assessed the effect of pre‐rice vegetation on conserving this NO₃‐N as well as on N addition by biological N₂ fixation in legumes using δ¹⁵N isotope dilution. Finally, we determined the impact of soil N fluxes and their differential management during the transition season on growth, yield and N use of rainfed lowland rice. Results : Following the first rainfall event of the season, soil NO₃‐N initially accumulated and subsequently decreased gradually in the soil of the valley slope. Much of this nitrate N was translocated by lateral sub‐surface flow into the valley bottom wetland. There, pre‐rice vegetation was able to absorb much of the in‐situ mineralized and the laterally‐translocated soil NO₃‐N, reducing its accumulation in the soil from 40–43 kg N ha^?1 under a bare fallow to 1–23 kg N ha^?1 in soils covered by vegetation. Nitrogen accumulation in the biomass of the transition season crops ranged from 44 to 79 kg N ha^?1 with a 36–39% contribution from biological N₂ fixation in the case of legumes. Rice agronomic performance improved following the incorporation as green manure of this “nitrate catching” vegetation, with yields increasing up to 3.5 t ha^?1 with N₂‐fixing transition seasons crops. Conclusion : Thus, integrating transition season legumes during the pre‐rice cropping niche in the prevailing low‐input systems in inland valleys of the dry savanna zone of West Africa can temporarily conserve substantial amounts of soil NO₃‐N. It can also add biologically‐fixed N, thus contributing to increase rice yields in the short‐term and, in the long‐term, possibly maintaining or improving soil fertility in the lowland.     

Effects of Rhizobial inoculant and nitrogen fertilizer on yield and nodulation of common bean

A two‐year field experiment was conducted to determine if using mixed strains of Rhizobium inoculant and starter nitrogen (N) fertilizer could improve yield and nodulation of four common bean varieties on a Vertisol at Alemaya, Ethiopia. A granular mixed inoculant of CIAT isolates 384, 274, and 632 and a starter N fertilizer at a rate of 23 kg N ha^‐1 (50 kg urea ha^‐1) were applied separately at planting. Inoculation with mixed strains and starter N fertilizer gave a significantly higher grain yield, nodule number, and dry matter yield for most varieties used. Both grain yield and dry matter yield showed a significant correlation (r=0.93 and r=0.87; P<0.05 for grain yield and dry matter yield, respectively, for 1991 crop season and r=0.90 and r=0.86; P<0.05 for grain yield and dry matter yield, respectively, for 1992 crop season) with nodule number. It is recommended that resource‐poor farmers adopt the practice of using a Rhizobium inoculant or starter N to improve common bean yields in the Hararghe highlands, Ethiopia.     

Modeling Effects of Soil Fertility of Nutrients and Precipitation of 22 Years on Sustainable Productivity and Profitability of Pearlmillet and Sorghum Rotation in Semi-arid Vertisols

Based on experiments conducted during 1988–2009 on rainfed pearl millet/sorghum with 9 treatments in Vertisols, an efficient treatment for sustainable productivity is identified. Twenty kg of nitrogen (N) from farmyard manure (FYM) + 20 kg N (urea) + 10 kg phosphorus (P) ha^?1 in pearl millet and 40 kg N (urea) + 20 kg P + 25 kg zinc sulfate (ZnSO₄) ha^?1 in sorghum gave maximum yield and rainwater-use efficiency, whereas 20 kg N (FYM) + 20 kg (urea) + 10 kg P ha^?1 in pearl millet and 40 kg (urea) + 20 kg P ha^?1 in sorghum and gave maximum soil N, P, and potassium (K) over years. The regression model of 20 kg N (crop residue) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² for predicting sorghum equivalent yield separately through precipitation and soil variables, whereas 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 gave maximum R² under combined model of both variables. Treatment of 20 kg N (FYM) + 20 kg N (urea) + 10 kg P ha^?1 was superior for attaining maximum sorghum equivalent yield of 1062 kg ha^?1, net returns of Rs. 4805 ha^?1, benefit/cost (BC) ratio of 1.50, and 127 kg ha^?1 of soil N, 10.3 kg ha^?1 of soil P, and 386 kg ha^?1 of soil K over years.     

Long-Term Tillage,Straw Management,and Nitrogen Fertilization Effects on Organic Matter and Mineralizable Carbon and Nitrogen in a Black Chernozem Soil

Soil, crop, and fertilizer management practices may affect quality of organic carbon (C) and nitrogen (N) in soil. A long-term field experiment (growing barley, wheat, or canola)was conducted on a Black Chernozem (Albic Argicryoll) loam at Ellerslie, Alberta, Canada, to determine the influence of 19 years (1980 to 1998) of tillage [zero tillage (ZT) and conventional tillage (CT)], straw management [straw removed (S_Rem) and straw retained (S_Ret)], and N fertilizer rate (0, 50, and 100 kg N ha^?1 in S_Ret and 0 kg N ha^?1 in S_Rem plots) on macro-organic matter C (MOM-C) and N (MOM-N), microbial biomass C (MB-C), and mineralizable C (C_min) and N (N_min) in the 0- to 7.5-cm and 7.5- to 15-cm soil layers. Treatments with N fertilizer and S_Ret generally had a greater mass of MOM-C (by 201 kg C ha^?1 with 100 kg N ha^?1 rate and by 254 kg C ha^?1 with S_Ret), MOM-N (by 12.4 kg N ha^?1 with 100 kg N ha^?1 rate and by 8.0 kg N ha^?1 with S_Ret), C_min(by 146 kg C ha^?1 with 100 kg N ha^?1 rate and by 44 kg C ha^?1 with S_Ret), and N_min(by 7.9 kg N ha^?1 with 100 kg N ha^?1 rate and by 9.0 kg N ha^?1 with S_Ret)in soil than the corresponding zero-N and S_Rem treatments. Tillage, straw, and N fertilizer had no consistent effect on MB-C in soil. Correlations between these dynamic soil organic C or N fractions were strong and significant in most cases, except for MB-C, which had no significant correlation with MOM-C and MOM-N. Linear regressions between crop residue C input and mass of MOM-C, MOM-N, C_min, and N_min in soil were significant, but it was not significant for MB-C. The effects of management practices on dynamic soil organic C and N fractions were more pronounced in the 0- to 7.5-cm surface soil layer than in the 7.5- to 15-cm subsoil layer. In conclusion, the findings suggest that application of N fertilizer and retention of straw would improve soil quality by increasing macro-organic matter and N-supplying power of soil.     

Nitrogen source and application method impact on corn yield and nutrient uptake

Farmers are looking for better management practices to utilize animal manure as an alternative to chemical fertilizers. A 2-year field experiment was conducted to study the effects of nitrogen (N) fertilizer source and application methods to Nicholson silt loam soil in central Kentucky, USA for no-till corn (Zea mays) production. The region has a temperate climate with a mean temperature of 14.5°C and rainfall of 1300 mm year^?1. Treatments included a control, 179 kg N ha^?1 urea ammonium nitrate (UAN) applied as preplant and sidedress, and swine effluent that was applied by three methods: broadcast, injection, and Aerway. Injection method produced the greatest corn grain yield (11.88 Mg ha^?1) and biomass yield (18.9 Mg ha^?1) in 2007. Results demonstrated that the effluent application methods and the timing of UAN application may not be agronomically important for corn production in this region. Hence, more studies are needed on different soils in this region.