Effect of nitrogen sources on the yield of common bean (Phaseolus vulgaris) in western Kenya

Depletion of soil nutrients due to continuous cultivation without adequate external fertilization is one of the challenges facing many smallholder farmers in western Kenya. This study was conducted to assess the effects of organic (water hyacinth compost), inorganic (urea) nitrogen (N) sources, and commercial Rhizobia inoculant on the yield of common bean (Phaseolus vulgaris) for two consecutive seasons in the short rains (2013) and long rains (2014). The experiments were laid out in a randomized complete block design and replicated four times. Triple superphosphate was applied to all treatments except those with compost to ensure that the soil had adequate phosphorus (P). Yellow and Rose coco bean varieties grown with urea and inoculated with commercial Rhizobia inoculant gave significantly higher yield of 382 kg ha^?1 and 341 kg ha^?1, respectively in the short rains (SR) season. In the long rains (LR) season bean yield was high in water hyacinth compost (1526 kg ha^?1) and control with non-limiting P (1300 kg ha^?1) treatments. Commercial Rhizobia inoculant did not significantly increase in yield in the SR and LR seasons. There was no significant influence on soil properties after two seasons of continuous cultivation of common bean and application of organic and inorganic fertilizers. These results demonstrate that water hyacinth compost improved bean yield in the LR season. However, longer field testing and economic analysis are required for it to be recommended as a substitute for inorganic N source among smallholder farmers.     

Effectiveness of native Rhizobium on nodulation and yield of faba bean (Vicia faba L.) in Eastern Ethiopia

This study was initiated to evaluate the effect of locally isolated Rhizobium on nodulation and yield of faba bean at Haramaya, Ethiopia for three consecutive years. Ten treatments comprising of eight effective isolates of rhizobia, uninoculated, and N-fertilized (20 kg N ha^?1) were laid out in a randomized complete block design with three replications. The result of the experiment indicated that all inoculation treatments increased nodule number and dry weight over the control check in all cropping seasons. The result, however, showed the non-significant effect of Rhizobium inoculation on shoot length, number of tiller per plant and 100 seed weight in all cropping season. Inoculating Haramaya University Faba Bean Rhizobium (HUFBR)-15 in 2011 and National Soil Faba Bean Rhizobium (NSFBR)-30 in 2012 and 2013 gave the highest grain yields (4330, 5267 and 4608 kg ha^?1), respectively. These records were 75%, 48%, and 5% over the uninoculated treatment of respective years. Over the season, NSCBR-30 inoculation resulted in the highest nodulation and grain yield production as compared to the other treatments. In general, isolates from central Ethiopia were better than those isolated from eastern Ethiopia and Tropical Agricultural Legume (TAL)-1035 in enhancing faba bean production at Haramaya site. Therefore, NSFBR-30 is recommended as a candidate isolate for faba bean biofertilizer production in eastern Ethiopia soils.     

Is it possible to attain high-yielding common bean using molybdenum fertilizer instead of side-dressed nitrogen?

We evaluate the feasibility of using foliar-applied molybdenum, (Mo) instead of side-dressed nitrogen (N) in three experiments. In soils with native rhizobia, plants received 0, 30, 60, 90 or 120 kg N ha^?1 with +Mo (80 g ha^?1) or -Mo. N concentration in leaves (NCL) -Mo ranged from 35.1 to 42.5 g kg^?1 and NCL +Mo from 40.3 to 49.2 g kg^?1; yield -Mo ranged from 1560 to 3350 kg ha^?1and yield +Mo from 2829 to 3567 kg ha^?1. In two experiments, NCL or yield -Mo increased linearly or quadratically with increasing N rates, but NCL or yield +Mo did not. In one experiment, NCL increased linearly with increasing N rates and 16% with +Mo relative to –Mo, but yield was not affected significantly. Our results suggest that using Mo fertilizer instead of side-dressed N can allow common bean plants to meet crop demands for N to support yields as high as 3000 kg ha^?1.     

Soil-Test-Based Optimum Fertilizer Doses for Attaining Yield Targets of Rice under Midland Alfisols of Eastern India

Soil-test crop-response experiments on rice were conducted in the Bastar Plateau Agroclimatic Zone of Chhattisgarh during 2009–2011 to assess yield, soil, plant, and fertilizer nitrogen (N), phosphorus (P), and potassium (K) nutrient relationships and calibrate optimum fertilizer doses for attaining yield targets. Soil fertility status was poor to medium for N (194–283 kg ha^?1) and P (7.53–19.66 kg ha^?1), and medium to good for K (226–320 kg ha^?1). Based on nutrient requirements (NR, kg q^?1) and contributions from soil (CS, %), fertilizer (CF, %), and farmyard manure (CFYM, %), optimum fertilizer doses were derived. The fertilizer doses were validated for attaining yield targets of 5000 and 6000 kg ha^?1 in farmer’s fields. Rice yield within 10% deviation was attained, which indicated that soil-test-based fertilizer dose was superior. This approach could be adopted for regions with similar soil and agroclimatic conditions in other parts of the world to increase rice yields.     

Potassium fertilization and soil diagnostic criteria for forage corn (Zea mays L.) production contributing to lower potassium input in regional fertilizer recommendation

Abstract

Effective soil diagnostic criteria for exchangeable potassium (Ex-K) combined with inorganic potassium (K) application rates were developed to lower K input in forage corn (Zea mays L.) production using experimental fields with different application rates and histories of cattle manure compost. Two corn varieties, ‘Cecilia’ as a low K uptake variety and ‘Yumechikara’ as a high K uptake variety, were selected from among 20 varieties and tested to make diagnostic criteria for K fertilization applicable to varieties with different K uptakes. The K uptakes increased from 96 to 303 kg K ha^?1 for ‘Cecilia’ and from 123 to 411 kg K ha^?1 for ‘Yumechikara’ with increasing Ex-K content on a dry soil basis from 0.11 to 0.92 g kg^?1 with no inorganic K fertilizer application. The K uptake by corn for achieving the target dry matter yield of 18 Mg ha^?1 was estimated to be approximately 200 kg K ha^?1 in common between the two varieties. Yields of both varieties achieved the target yield at an Ex-K content of approximately 0.30 g kg^?1 with no K fertilization, although ‘Yumechikara’ reached the target yield at a lower Ex-K content. At the low Ex-K content of 0.1 g kg^?1, inorganic K fertilizer application at 83 kg K ha^?1 was needed to gain the target yield, and apparent K recovery rate for K fertilizer was calculated to be 70% for both varieties. The K uptakes for gaining the target yield by the K fertilization were lower than that by soil K supply. Based on these results, diagnostic criteria of Ex-K and inorganic K application rates were set up as follows: at an Ex-K content of < 0.15 g kg^?1, inorganic K fertilizer is applied at 83 kg K ha^?1 (100 kg ha^?1 as potassium oxide (K₂O) equivalent); at an Ex-K content of 0.15–0.30 g kg^?1, the application rate is reduced to 33 kg K ha^?1 (40 kg K₂O ha^?1); at an Ex-K content of ≥ 0.30 g kg^?1, inorganic K fertilizer is not applied because of sufficient K in the soil. Additionally, we propose that cattle manure compost be used to supplement soil K fertility.     

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.     

Effect of 13 Years Long Minimum Tillage Cum Conjunctive Nutrient Management Practices on Soil Fertility and Nitrogen Chemical Fractions under Sorghum (Sorghum bicolour (L.) Moench)–Mungbean (Vigna radiata (L.) Wilczek) System in Semi-Arid Tropical Alfisol (SAT) in Southern India

A long-term experiment was conducted at the Central Research Institute for Dryland Agriculture for 13 years to evaluate the effect of low tillage cum cheaper conjunctive nutrient management practices in terms of productivity, soil fertility, and nitrogen chemical pools of soil under sorghum–mung bean system in Alfisol soils. The results of the study clearly revealed that sorghum and mung bean grain yield as influenced by low tillage and conjunctive nutrient management practices varied from 764 to 1792 and 603 to 1008 kg ha^?1 with an average yield of 1458 and 805 kg ha^?1 over a period of 13 years, respectively. Of the tillage practices, conventional tillage (CT) maintained 11.0% higher yields (1534 kg ha^?1) over the minimum tillage (MT) (1382 kg ha^?1) practice. Among the conjunctive nutrient management treatments, the application of 2 t Gliricidia loppings + 20 kg nitrogen (N) through urea to sorghum crop recorded significantly highest grain yield of 1712 kg ha^?1 followed by application of 4 t compost + 20 kg N through urea (1650 kg ha^?1) as well as 40 kg N through urea alone (1594 kg ha^?1). Similar to sorghum, in case of mung bean also, CT exhibited a significant influence on mung bean grain yields (888 kg ha^?1) which was 6.7% higher compared to MT (832 kg ha^?1). Among all the conjunctive nutrient management treatments, 2 t compost + 10 kg N through urea and 2 t compost + 1 t Gliricidia loppings performed significantly well and recorded similar mung bean grain yields of 960 kg ha^?1 followed by 1 t Gliricidia loppings + 10 kg N through urea (930 kg ha^?1). The soil nitrogen chemical fractions (SNCFs) were also found to be significantly influenced by tillage and conjunctive nutrient management treatments. Further, a significant correlation of SNCF with total soil nitrogen was observed. In the correlation study, it was also observed that N fraction dynamically played an important role in enhancing the availability pool of N in soil and significantly influenced the yield of sorghum grain and mung bean.     

Integrated Fertilizer Management: Influence on Soil Nitrogen,Available Phosphorus,Potassium, Nutrient Uptake and Maize Yield

A field experiment was conducted on an Alfisol (kandic paleustalf) in Abeokuta, Southwestern Nigeria, for two seasons to assess the influence of inorganic and organic fertilizers on nitrogen (N), phosphorus (P), potassium (K), nutrient uptake and maize yield. The treatments consisted of three rates of organic fertilizer 0, 5 and 10 t ha^?1 in the form of poultry manure and NPK fertilizer (20:10:10) applied at 0 and 120 kg ha^?1. Maize (Zea mays) was used as the test crop. The results showed that the combined application of 10 t ha^?1 poultry manure and 120 kg ha^?1 NPK fertilizer enhanced the uptake of N, P and K better than other treatment combinations. Application of 10 t ha^?1 poultry manure alone gave the highest grain yield, which was 67.02% higher than the control in the first season. Complementary application of 5 t ha^?1 poultry manure with 120 kg ha^?1 NPK 20–10-10 was recommended for grain yield.     

Real-time nitrogen management in aerobic rice by adopting leaf color chart (LCC) as influenced by silicon

Leaf color chart (LCC) guides fertilizer nitrogen (N) application to rice as per requirement of the crop on the basis of a critical leaf color. Two field experiments were conducted to evaluate the effect of silicon (Si) and LCC based N management in aerobic rice. Following LCC-based N management, from 60 to 90 kg N ha^?1 and 75 to 100 kg N ha^?1 with 10–40% and 25–30% less fertilizer N was used without any reduction in yield as compared to the package of practices of 100 (50 kg N ha^?1 as basal + two split of 25 kg N ha^?1) kg N ha^?1 respectively, during both the seasons. The highest grain yield was noticed with 90 kg N ha^?1 (30 kg N ha^?1 as basal + LCC-3) and 100 kg N ha^?1 (50 kg N ha^?1 as basal + two split of 25 kg N ha^?1) along with the application of calcium silicate (CaSiO₃) at 2 t ha^?1 as sources of Si and on par with 60 kg N ha^?1 (no basal + LCC-3) and 75 kg N ha^?1 (30 kg N ha^?1 as basal + LCC-3), respectively, during the season in 2008 and 2009. Higher fertilizer N use efficiency was recorded with Si and need-based N management using LCC-3 rather than recommended dose of fertilizer N.     

Biochar and inorganic nitrogen fertilizer effects on maize (Zea mays L.) nitrogen use and yield in moist semi-deciduous forest zone of Ghana

Abstract

Maize (Zea mays L.) is a major nitrogen consuming crop, as nitrogen is considered as an important determinant of its grain yield. Though inorganic fertilizer is widely recommended, the problem of high cost and inaccessibility limit its usage by resource poor farmers. Biochar application provides a new technology for both soil fertility and crop productivity improvement. With limited research on the suitability of biochar for soil improvement practices in Ghana, our objective was to determine the synergistic effect of biochar and inorganic fertilizer on the nitrogen uptake, nitrogen use efficiency, and yield of maize. Field experiment was conducted in Ghana, KNUST, in the major and minor raining seasons. Biochar was applied at 0, 5, 10, 15, and 20 t ha^?1 and fertilizer N applied at 0, 45, and 90?kg ha^?1. The results showed significantly (p??1 supplemented with 45?kg N ha^?1 increased N uptake by 200%, and grain yield by 213% and 160% relative to the control in the minor and major rainy seasons, respectively. The greater yield of maize recorded on biochar-amended soils was attributed to the improved N uptake and nitrogen use efficiency. In conclusion, our finding suggests that the application of combined biochar and inorganic N fertilizer is not only ecologically prudent, but economically viable and a practicable alternative to current farmers’ practice of cultivating maize in Ghana.     

Spring camelina N rate: balancing agronomics and environmental risk in United States Corn Belt

Camelina (Camelina sativa (L.) Crantz) seed oil has desirable properties for producing advanced biofuels and as a healthy cooking oil. It has been grown for centuries, but basic recommendations for nitrogen (N) fertilizer requirements are still needed to support widespread industrial cultivation across North America. A replicated N-response plot-scale study was conducted on a northern Mollisol soil for two growing seasons to 1) determine seed and oil yield, seed oil content, and vegetative response; 2) determine indices of N use efficiency; and 3) measure post-harvest residual inorganic soil N as an index of environmental risk. Seed and oil yield response to N fertilization was described with a quadratic function, which predicted maximum seed yield (1450 kg ha^?1) and oil yield (580 kg ha^?1) at about 130 kg N ha^?1. However, seed and oil yield did not differ significantly among N-rates above 34 kg N ha^?1. Seed oil content averaged 400 g kg^?1 among all N rates. Agronomic efficiency declined above 34 kg N ha^?1, which coincided with an increase of post-harvest soil nitrate-N plus ammonium-N (residual N). Considering N use efficiency, simple cost analysis, and risk associated with residual N, a rate of 34 kg N ha^?1 is recommended.     

Effect of rates and sources of nitrogen on rice yield,nitrogen efficiency,and methane emission from irrigated rice cultivation

The agronomic benefits of manure application to increase rice production have been recognized, but the impact on global change has always been a controversial topic. This study was designed to determine the separate and combined effects of cattle manure (CM) and nitrogen (N) fertilizer on rice yield, N efficiency, and methane (CH₄) emissions from rice cultivation. A pot-scale experiment was conducted with four levels (0, 60, 120, and 180 kg ha^?1) of N from urea and two levels (120 and 180 kg ha^?1) of N from combination of urea and CM (Urea:CM = 60:60 and 60:120). Rice yield and physiological N efficiency were obtained using agronomic measurements. To determine the global warming potential (GWP) of each treatment, CH₄ emissions were measured throughout the rice-growing period. Grain yield (GY) was not significantly different between the treatments of 120 and 180 kg ha^?1 regardless of N source. However, both rates of CM treatments enhanced CH₄ emission and differences in GWP were significant. In conclusion, urea applied at 120 kg N ha^?1 was optimal for rice productivity and environmental impact (EI) despite CM played a crucial role in improving the N efficiency and total N in the soil after harvest.     

Response surface optimization of cultivation conditions for yield of tomato (Lycopersicon esculentum Mill.) in greenhouses

There is a great potential for greenhouse tomato fruit yield improvement in China for the low yield per hectare. We evaluated the effects of multi-factors (plant density, nitrogen (N) and K₂O fertilizer) on fruit yield of tomato (Lycopersicon esculentum Mill. cv. Jinfan 4) by response surface methodology with a 5-level-3-factor central composite design. A multivariate quadratic regression model of fruit yield was established. Results showed that N fertilizer was the most significant for fruit yield, followed by K₂O fertilizer and plant density. Fruit yield showed a parabolic trend with increasing fertilizer levels or plant density. There was a significant interaction effect between plant density and fertilizer levels. Optimal conditions were obtained: 4.83 × 10⁴ plants ha^?1 for density, 262 kg ha^?1 for N and 513 kg ha^?1 for K₂O. Under these conditions, the predicted fruit yield was 119,381 kg ha^?1, while the actual fruit yield from verification test was 121,005 kg ha^?1.     

Microbial inoculation of Rhizobium and phosphate-solubilizing bacteria along with inorganic fertilizers for sustainable yield of soybean [Glycine max (L.) Merrill]

A field experiment was conducted to assess the effect of microbial inoculants and inorganic fertilizers for sustaining the yield of soybean. Application of 100% recommended dose of fertilizer (RDF) gave significantly highest yield (2433 kg ha^?1) over 75% RDF (2317 kg ha^?1) and without RDF (2205 kg ha^?1). Seeds inoculated with Rhizobium (Bradyrhizobium japonicum) and phosphate-solubilizing bacteria (2480 kg ha^?1) gave significantly highest soybean yield over without inoculation (2191 kg ha^?1). Rhizobium and phosphate-solubilizing bacteria with 100% RDF (2674 kg ha^?1) gave significantly highest seed yield than rest of the treatment combinations. Root nodules and their dry weight were remained un-influenced due to fertilizer levels, whereas in bio-fertilizers, it was significantly higher with Rhizobium inoculation (24.3 and 408 mg, respectively) followed by dual inoculation of Rhizobium and PSB. 100% RDF and dual inoculation with Rhizobium and PSB earned Rs. 47916/- and Rs. 51182/- net returns per ha, respectively.     

Study on the Effects of Organic and Inorganic Nitrogen Fertilizer on Yield,Yield Components,and Nodulation State of Chickpea (Cicer arietinum L.)

To study the effects of organic and inorganic nitrogen (N) on yield and nodulation of chickpea (Cicer arietinum L.) cv. ILC 482, a spilt-plot experiment based on randomized complete block design with four replications was conducted in 2008 at the experimental farm of the Agriculture Faculty, University of Mohaghegh, Ardabili. Experimental factors were inorganic N fertilizer at four levels (0, 50, 75, and 100 kg ha^?1) in the main plots that applied in the urea form, and two levels of inoculation with Rhizobium bacteria (with and without inoculation) as subplots. Nitrogen application and Rh. inoculation continued to have positive effects on yield and its attributes. The greatest plant height, number of primary and secondary branches, number of pods per plant, number of filled and unfilled pods per plant, number of grains per plant, grain yield, and biological yield were obtained from the greatest level of N fertilizer (100 kg urea ha^?1) and Rh. inoculation. Application of 75 and 100 kg ha^?1 urea showed no significant difference in these traits. Furthermore, the greatest rate of N usage (100 kg urea ha^?1) adversely inhibited nodulation of chickpea. Number and dry weight of nodules per plant decreased significantly with increasing N application rate. The lowest values of these traits recorded in application of 100 kg ha^?1 urea. Results indicated that application of suitable amounts of N fertilizer (i.e., between 50 and 75 kg urea ha^?1) as starter can be beneficial to improve nodulation, growth, and final yield of inoculated chickpea plants.     

Nitrogen Management for Sustainable Soil Organic Carbon Increase in Inceptisols Under Wheat Cultivation

Application of nitrogen (N) fertilizers to increase crop yield is a worldwide practice, which also has a positive influence on the soil organic carbon (SOC) increase. This study was carried out to investigate the dynamics of SOC and its fractions under different levels of N fertilization in wheat grown inceptisols of Northeast India over a period of 2 years. For the purpose of this study, fertilizer treatments with five N levels (40, 60, 72, 80, and 100 kg N ha^?1) were applied in randomized block design. Increased SOC particulate organic carbon (POC), humic acid carbon, and fulvic acid carbon were recorded under application of higher N. Stability of SOC as indicated by E4/E6 ratio and microbial biomass carbon (MBC) was higher on application of 72 kg N ha^?1. Among the SOC fractions, POC and MBC respond rapidly to different N fertilization rates. Available N and phosphatase activity increased while pH and urease activity (UA) decreased as a function of applied N fertilizer levels. Nitrogen fertilization increased wheat yield and biomass with insignificant differences among 100, 80, and 72 kg N ha^?1. Thus, under the present experimental conditions, application of 72 kg N ha^?1 can sustain SOC and soil health without compromising wheat yield in the inceptisols of Northeast India.     

Evaluation of White yam (Dioscorea rotundata) genotypes for arbuscular mycorrhizal colonization,leaf nutrient concentrations and tuber yield under NPK fertilizer application

Yield decline in yam may not only be due to soil nutrient depletion but also to the activity of soil microflora. Arbuscular mycorrhizal (AM) symbiosis helps in plant nutrition but may be affected by the application of fertilizer. The effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates on the AM colonization, leaf nutrient concentrations, and tuber yields of eleven genotypes of Dioscorea rotundata were investigated at Ibadan, Nigeria. The soil was ferric luvisol. Eleven genotypes were selected from the previously conducted screening of 75 genotypes of D. rotundata for fertilizer response. Four application rates: 0, 200, 400, and 600 kg ha^?1 of NPK 15-15-15 were applied in a split plot design with four replications. Fertilizer rate was the main plot and variety was the sub plot. Percentage AM colonization was significantly reduced at 600 kg ha^?1 but not at lower rates when compared to zero rate and it was negatively correlated with leaf N, P, and zinc (Zn) concentrations. Leaf N concentrations were significantly increased at 200 kg ha^?1 in five genotypes and at 600 kg ha^?1 in two genotypes compared to zero application. Leaf P and K concentrations were decreased with the application of fertilizer in most of the genotypes. The NPK fertilizer of 15-15-15 at the rate of 200–400 kg ha^?1 gave yield response in eight genotypes of D. rotundata, with minimal or no effect on their AM colonization when compared to zero application. Long term study on the effect of fertilizer application on AM symbiosis in yam is recommended.     

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 FERTILIZER MANAGEMENT FOR IMPROVED GRAIN QUALITY AND YIELD IN WINTER WHEAT IN OKLAHOMA

From 2002 to date, a long-term field experiment has been conducted at Lake Carl Blackwell, Oklahoma, with different rates and times of nitrogen (N) fertilizer application to determine their effect on grain yield, protein and N uptake of winter wheat. Trend analysis for N rates (0, 50, 100, 150 and 200 kg N ha^?1) and orthogonal contrasts for different application times (pre-plant, top-dressed in February and March) were performed. With increasing fertilizer N, wheat grain yield and protein content increased from 2110 kg ha^?1 to 6783 kg ha^?1 and from 8.96 to 17.19%, respectively. For grain yield, protein, and N use efficiency, split applications of N fertilizer were much more efficient than applying all N pre-plant. Large differences in grain yields were noted for different years at the same N rate (range exceeded 5.0 Mg ha^?1) and that illustrated the need for making within-year-specific N rate recommendations.     

EFFECTS OF CARBONIZED CHICKEN MANURE ON THE GROWTH,NODULATION, YIELD,NITROGEN AND PHOSPHORUS CONTENTS OF FOUR GRAIN LEGUMES

The effects of carbonized chicken manure (CCM) on the growth, nodulation, yield, nitrogen (N) and phosphorus (P) contents of four grain legumes (soybean, cowpea, common bean and adzuki bean) were evaluated in a greenhouse experiment. Carbonized chicken manure produced from chicken manure dried in a furnace at 450°C was used in this experiment. The manure was incorporated into the sandy loam soil of each grain legume at two rates (0 kg N ha^?1 and 100 kg N ha^?1) three weeks before sowing. Growth, nodulation and total biomass N and P were evaluated at peak flowering stage of growth. The CCM showed positive effects on nodule number and weight of soybean and cowpea while it depressed nodule number in adzuki bean. Biomass total N content of soybean and cowpea increased with CCM supply while it decreased in adzuki bean. Biomass and seed total P content of soybean, cowpea and adzuki bean all increased in response to CCM application. Soybean and cowpea seed yields increased by 27% and 43% respectively in response to CCM supply. There was a strong positive correlation between seed P content and seed yield of soybean which indicates the importance of elemental P to soybean seed yield. No such phenomenon was observed in adzuki bean. A strong positive correlation was also observed between seed total N content and seed yield of the grain legumes. The results indicate that although common bean had the highest biomass total P content at peak flowering stage both vegetative and reproductive growth were poor due to the unsuitably high day/night temperatures in the greenhouse. Application of CCM slightly depressed yield of adzuki bean due to the reduction in the number of pods per pot and the 100 seed weight. This study shows that CCM is a good source of N and P for the growth, nodulation and yield of some grain legumes particularly soybean and cowpea.