NITROGEN,PHOSPHORUS, AND POTASSIUM EFFECTS ON GRAIN SORGHUM PRODUCTION AND STALK ROT FOLLOWING ALFALFA AND BIRDSFOOT TREFOIL

Grain sorghum [Sorghum bicolor (L.)], grown on the often infertile claypan soils of the eastern Great Plains, requires attention to soil fertility. Experimental objectives were to determine the effects of phosphorus (P) and potassium (K) fertility levels, N application, and legume residual on grain sorghum production and stalk rot. Following alfalfa and birdsfoot trefoil, first-year sorghum yield was 7 Mg ha^?1 and not affected by N fertilizer. In subsequent years, yield increases due to N were less than 20%. Sorghum yield increased at low P and K rates, especially with nitrogen (N) fertilization and was greater following birdsfoot trefoil than following alfalfa. In 1995 when fertilized with N, lodging and stalk rot severity were increased by P and reduced by K. In 1996, stalk rot severity was reduced by K fertilization. Grain sorghum, grown after legume crops, required minimal levels of P and K, especially when N fertilizer was added.     

Phosphorus,potassium, chloride,and fungicide effects on wheat yield and leaf rust severity

Abstract

Plant nutrition and disease suppression are among the most important management tools for producers of hard red winter wheat (Triticum aestivum L.) in the central and southern Great Plains. This study was conducted to examine the effects of phosphorus (P) (0, 15, and 30 kg ha^?1) and potassium (K) (0, 37, and 74 kg ha^?1) fertilization, foliar fungicide application, and cultivar disease tolerance on wheat yield, yield components, and severity of leaf rust (Puccinia triticina Eriks.). Compared with no P, fertilizing with P increased yield by as much as 60% (>1.3 Mg ha^?1 increase). Yield of cultivars susceptible to leaf rust was nearly 0.6 Mg ha^?1 less without K than with K fertilization. Fungicide application resulted in mean yields of 4.8 Mg ha^?1 for both resistant and susceptible cultivars, however, yield of susceptible cultivars was suppressed more than yield of resistant ones without fungicide. Although P fertilization had a moderately suppressive effect on leaf rust, the increased yield was primarily due to production of about 50% more heads m^?2 apparently from more prolific tillering. Similarly, K fertilization appeared to reduce leaf rust severity and improve yield by increasing kernel weight, but this response may have been related partially to chloride (Cl) in the KCl fertilizer. Correlations suggested that improving dry matter production and N, P, and K uptakes at the boot stage by P and K fertilization can reduce leaf rust severity later in the growing season and increase wheat grain yield. These results indicate that especially P fertilization, but also K fertilization and fungicide application, are important management tools for reducing disease and increasing winter wheat yield.     

EFFECT OF NITROGEN APPLICATION ON ACCUMULATION AND TRANSLOCATION OF CARBON AND NITROGEN COMPOUNDS IN TWO MAIZE CULTIVARS WITH DIFFERENT SENESCENT APPEARANCE

Field experiments and plant analyses were carried out to investigate the effect of nitrogen (N) application on accumulation and translocation of carbon (C) and N compounds in two maize (Zea mays L.) cultivars with different senescent appearance. Two maize hybrids included “Danyu 13”, an earlier senescent hybrid, and “Simi 21”, a stay-green hybrid. There were four nitrogen treatments: (1) N1: 0 kg N ha^?1, (2) N2: 250 kg N ha^?1 (1/5 N as basal application and 4/5 N as top-dressing at stalk elongation stage only), (3) N3: 250 kg N ha^?1 (1/5 N as basal, 2/5 N as top-dressing at stalk elongation stage and tasselling stage, respectively), (4) N4: 400 kg N ha^?1 (1/5 N as basal and 4/5 N as top-dressing at stalk elongation stage). For Simi 21, a higher percentage of sugar and starch were found in each treatment in root, stem, leaf and grain, in comparison with that for Danyu 13. The highest percentage of sugar and starch, 80% ethanol-soluble N and soluble protein N in each organ could be achieved in N3 treatment for Simi 21 and in N2 treatment for Danyu 13, respectively, which consequently benefited to translocation of C and N from vegetative parts to grain. Excessive N could not produce the highest percentage of sugar and starch, 80% ethanol-soluble N and soluble protein N, but the highest percentage of residue C and N components in each organ for both hybrids.     

Effect of Vermicompost and Chemical Fertilizer on Growth,Herb, Oil Yield,Nutrient Uptake,Soil Fertility,and Oil Quality of Rosemary

Essential oil of rosemary (Rosmarinus officinalis L.) possesses good olfactory properties and is suitable for use in perfumes, soaps, and fragrances. Field experiments were conducted for 2 years (2003?2005) in an area experiencing a semi-arid tropical climate to study the influence of vermicompost and chemical fertilizer on growth, herb, oil yield, nutrient uptake, soil fertility, and oil quality of rosemary. Results from the experiment revealed that among the seven treatments, the application of vermicompost (8 t ha^?1) + fertilizer nitrogen (N)?phosphorus (P)??potassium (K) (150:25:25 kg ha^?1) produced optimum herbage and oil yield of rosemary compared with control (no fertilizer) and was found to be on par with application of fertilizer NPK 300:50:50 kg ha^?1. Content and quality of oil were not influenced by vermicompost and chemical fertilizers. Furthermore, it was noticed that available N and P were greater in postharvest soils that received vermicompost alone or in combination with inorganic fertilizers than control (no fertilizer) and inorganic fertilizer?treated soil. This study indicates that combined application of vermicompost and chemical fertilizer helps to increase crop productivity and sustain the soil fertility.     

Nutrient Uptake of Maize Affected by Nitrogen and Potassium Fertility in a Humid Subtropical Environment

Abstract

Nitrogen (N) and potassium (K) fertility management of maize (Zea mays L.) in the humid subtropical Mississippi Delta may differ from a temperate climate because of its use in rotation with cotton (Gossypium hirsutum L.), soil temperatures rarely falling to 0°C, and heavy winter rains that facilitate nutrient losses. An experiment to determine the [N] (concentration=[ ]), phosphorus [P], [K], calcium [Ca], magnesium [Mg], iron [Fe], manganese [Mn], zinc [Zn], and copper [Cu] and their total contents plant^?1 of maize grown in rotation with cotton, using N fertility levels of (134, 179, 224, 269, and 314 kg N ha^?1) in combination with K fertility levels of (0, 45, 90, and 134 kg K ha^?1) was conducted in 2000 and 2001 at Tribbett, MS. Ear leaves, immature ears, and husks collected at growth stage R2 and grain and stover collected 21 days after R6 were dried, weighed, and analyzed for nutrient concentration. Plots were also harvested for yield, kernel weight, grain bulk density, and harvest index (HI). Increased [N] values of about 1.3 mg g^?1 occurred in all organs except the stover between 134 and 314 kg N ha^?1 N fertility. Stover [N] increased approximately 3.0 mg g^?1 within the same N fertility range. Total N content of ear leaves, grain, and stover increased by about 11.0, 550.0, and 730.0 mg plant^?1, respectively, with N fertility increased from 134 to 314 kg N ha^?1. Yields, kernel weights, grain bulk densities, and harvest indices also increased with added N fertility. Several micronutrient concentrations and contents increased as N fertility increased. Increased K fertility had only limited influence on concentrations of most nutrient elements. The nutrient contents of most elements in the stover increased with added K fertility compared with plots that received no supplemental K fertilizer. These data showed between 139 and 265 kg N ha^?1 was permanently removed by grain harvest and suggest that N fertility recommendations for the Mississippi Delta may be low for maize yield goals above 10 Mg ha^?1. Added K fertilizer has minimal benefit to maize when soil test levels are adequate but are important to succeeding cotton crops where K uptake during fruiting can exceed the soil's ability to release K for uptake.     

Soil nutrient dynamics,growth and yield of green maize and vegetable cowpea with organic-based fertilization

The growth and yield performance of green maize (Zea mays), followed by a late-season vegetable cowpea (Vigna unguiculata), was assessed with two rates of three different types of organic-based fertilizers (OBFs) fortified with an inorganic nutrient source. There was also an inorganic fertilizer treatment of NPK 20–10–10 applied at 300 kg ha^?1 and a no-fertilizer control treatment. Maize growth was affected by fertilizer type and rate. Organic fertilizer, applied at 5 t ha^?1, 3 weeks before maize released enough nutrients to have comparable growth as inorganic fertilizer. Applying the OBF at 2.5 t ha^?1 was inadequate to give comparable growth. Application of fortified OBF with total nitrogen content higher than 2.4% N at 5.0 t ha^?1 gave maize grain yields comparable with NPK fertilizer. Cowpea yields following early-season maize were highest with DPW + NPK. They were significantly lower with 2.5 t ha^?1 of the OBFs. Application of the IAR&T-OBF (OBF made by Institute of Agricultural Research and Training) and decomposed poultry waste (DPW) + NPK at 5.0 t ha^?1 gave comparable seed yields significantly higher than OYO-OBF (OBF made by Oyo State Government of Nigeria). NPK fertilizer application supported early-season maize cultivation, but it was not adequate to support the following cowpea. OBF should have nitrogen content up to 2.4% and applied at 5.0 t ha^?1 to support an early-season maize cultivation with a late-season cowpea.     

Turkey Manure Ash Effects on Alfalfa Yield,Tissue Elemental Composition,and Chemical Soil Properties

A power plant that utilizes turkey manure as fuel to produce energy was built in Benson, Minnesota, and started full energy production in 2007. The plant was built to meet legislative requirements governing the use of renewable sources to generate energy in Minnesota. Although the use of turkey manure as biofuel generates energy, it also results in turkey manure ash (TMA) as a by‐product that contains phosphorus (P), potassium (K), sulfur (S), and zinc (Z) as well as other essential and nonessential elements. A 2‐year study was conducted to compare TMA with triple‐superphosphate and potassium chloride fertilizers as a source of nutrients for alfalfa (Medicago sativa) at three locations: Lamberton, Morris, and Appleton, Minnesota. The soils at Lamberton and Appleton were acidic with P and K concentrations ranging from medium‐high to very high, whereas the soil at Morris was alkaline with high concentrations of P and K. The experiment consisted of a control (0 P and 0 K) and annual and split applications of TMA and fertilizer. Annual TMA and fertilizer rates were 84 kg P₂O₅ ha^?1, 118 kg K₂O ha^?1, and 34 kg S ha^?1. Split rates were 42/42 kg P₂O₅ ha^?1, 59/59 kg K₂O ha^?1, and 17/17 kg S ha^?1. However, because of an overestimation of citrate‐soluble P in 2005 for the TMA, the total amount of available P applied with the TMA for the 2‐year study was 168 kg P₂O₅ ha^?1 compared with 286 kg P₂O₅ ha^?1 for the fertilizer. In the first year, fertilizer resulted in greater alfalfa biomass yield than TMA and the control, whereas in the second year, alfalfa yields with TMA and fertilizer were similar and both more than the control. In 2005, TMA resulted in more copper (Cu) and S tissue concentrations than the fertilizer. In 2006, application of both sources increased tissue P and S concentrations compared with the control. The TMA increased tissue Cu concentration and Zn plant uptake compared with fertilizer. Bray P1–extractable soil P concentrations were less with TMA and control treatments than with the fertilizer treatments. Ammonium acetate–extractable soil sodium (Na) concentrations were greater with TMA than with fertilizer and the control. By the second year, both ash and fertilizer treatments resulted in more K uptake than the untreated control with no difference in K uptake between the two sources or time of application. Both sources were effective in increasing P uptake compared with the untreated control. TMA was shown to be an effective source of nutrients for alfalfa production.     

Alkaline coal fly ash amendments are recommended for improving rice-peanut crops

Abstract

A field experiment investigating amendments of organic material including farmyard manure, paper factory sludge and crop residues combined with fly ash, lime and chemical fertilizer in a rice-peanut cropping system was conducted during 1997–98 and 1998–99 at the Indian Institute of Technology, Kharagpur, India. The soil was an acid lateritic (Halustaf) sandy loam. For rice, an N:P:K level of 90:26.2:33.3 kg ha^?1 was supplied through the organic materials and chemical fertilizer to all the treatments except control and fly ash alone. The required quantities of organic materials were added to supply 30 kg N ha^?1 and the balance amount of N, P and K was supplied through chemical fertilizer. Amendment materials as per fertilization treatments were incorporated to individual plots 15 days before planting of rice during the rainy season. The residual effects were studied on the following peanut crop with application of N:P:K at 30:26.2:33.3 kg ha^?1 through chemical fertilizer alone in all treatments, apart from the control. An application of fly ash at 10 t ha^?1 in combination with chemical fertilizer and organic materials increased the grain yield of rice by 11% compared to chemical fertilizer alone. The residual effect of both lime and fly ash applications combined with direct application of chemical fertilizer increased peanut yields by 30% and 24%, respectively, compared to chemical fertilizer alone. Treatments with fly ash or lime increased P and K uptake in both the crops and oil content in peanut kernel compared to those without the amendments. Alkaline coal fly ash proved to be a better amendment than lime for improving productivity of an acid lateritic soil and enriching the soil with P and K.     

Nitrogen topdressing at the jointing stage affects the nutrient accumulation and translocation in rainfed waxy maize

Timely and fitting nitrogen (N) application decreases costs and pollution risk in maize cultivation. To explore the accumulation and remobilization of dry matter (DM), N, phosphorus (P), and potassium (K) in waxy maize under various N topdressings (0?kg ha^?1, LN; 150?kg ha^?1, MN; 300?kg ha^?1, HN) at the jointing stage, a field trial involving two waxy maize varieties (Suyunuo 5 and Yunuo 7) was conducted in 2013–2016. The highest grain yield was obtained under MN mainly due to the highest grain numbers and grain weight. The increase in grain yield under MN was mainly due to the high DM accumulation post-silking, as well as high N, P, and K accumulation and remobilization pre-silking. Generally, the plants had high harvest index (HI) of DM (N, P, and K), partial N fertilizer productivity, and moderate N utilization efficiency (NUE) under MN.     

Grain yield,stalk rot,and mineral concentration of fertigated corn as influenced by N P K

Peanut (Arachis hypoaaea L.) is a major cash crop in Georgia. Corn (Zea mays L.) is the preferred rotation crop, but is often not profitable because of large inputs costs. Fertilizer comprises approximately 50% of the variable production costs of irrigated corn. There is interest in reducing fertilizer inputs, in particular N, to reduce variable costs and decrease nitrate leaching to groundwater, but yields may suffer. Our objective was to investigate the effect of N, P, and K fertilizer rates on the yield of N‐fertigated corn in a corn/peanut rotation. Field experiments were conducted during 1987 and 1988 on a Tifton loamy sand (fine‐loamy, siliceous, thermic Plinthic Paleudult) at Tifton, GA. Treatments were three rates each of N, P, and K fertilizer in a complete factorial. Nitrogen, P, and K rates were 168, 252, 336 kg N ha^‐1 yr^‐1; 44, 73, 103 kg P ha^‐1 yr^‐1; and 84, 223, and 363 kg K ha^‐1 yr^‐1, respectively. Grain yields were large, 12.6 and 10.4 Mg ha^‐1 in 1987 and 1988, respectively, but not affected by N, P, or K rate. Since the lower rates of N, P, and K were less than recommended, fertilizer use efficiency for fertigated corn can be improved, for at least one year, by reducing N, P, and K fertilizer rates to less than current recommendations. Rates of N, P, and K did not result in a substantial difference in the concentration of essential nutrients. Stalk rot was limited (< 15%), but decreased with increasing K fertilizer rate.     

FERTILIZER RATE EFFECTS ON FORAGE YIELD STABILITY AND NUTRIENT UPTAKE OF MIDLAND BERMUDAGRASS

Our objectives were to document effects of nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates on forage yields and uptake of N, P, and K by Midland bermudagrass [Cynodon dactylon (L.) Pers.] on a Minco fine, sandy loam in southern Oklahoma. After six years of this long-term experiment, forage yield responses to fertilization were mixed and depended on year. Stability analysis indicated forage yields responded positively to N fertilization during favorable weather conditions but negatively during poor weather conditions. Application of 112 kg N ha^?1 provided the best yield stability and mean annual forage yield among treatments, 11.5 Mg ha^?1, across years. In years with near-average weather conditions, uptake of N, P, and K increased linearly with N application rate. Limited water holding capacity of the soil and high soil P and K may have contributed to the limited yield responses to fertilization in this semi-arid environment.     

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.     

Nitrogen and phosphorous fertilizer improve pastures naturally growing under hazelnut trees

Abstract

This three-year study (2003–2005) aimed to improve the yield and quality of pastures growing naturally that are colonized by naturally occurring vegetation without agricultural input under hazelnut (Corylus sp.) orchards in the middle and eastern Black Sea regions of Turkey. There were eight treatments: 1) control; 2) fertilizer only (triple superphosphate 44% and calcium ammonium nitrate 26%) (80kg ha^?1 P and 60 kg ha^?1 N in Samsun; 100 kg ha^?1 P and 80 kg ha^?1 N in Ordu; 100 kg ha^?1 P and 40 kg ha^?1 N in Giresun); 3) lime only (calcium carbonate 94%) (3.0 t ha^?1 lime in Samsun; 4.5 t ha^?1 lime in Ordu and Giresun); 4) early cut only; 5) soil aeration only; 6) fertilizer+lime; 7) fertilizer+lime+early cut; 8) fertilizer+lime+soil aeration, laid out in a randomized complete block design with four replicates at each location. The highest dry matter (DM) yield of kg ha^?1 and crude protein content (%) was obtained from the treatments that included fertilizer. There was no difference in DM production between any of the combination treatments that involved fertilizer and the fertilizer alone treatment. Only lime and aeration applications also increased yield compared to control, but not as much as did any treatment including fertilizer. Crude protein content of the pasture ranged from 13.3 to 18.1% across locations. Nitrogen and phosphorus fertilizer are recommended to improve DM yields and herbage quality for pastures under hazelnut orchards.     

Improvement in Productivity,Water-Use Efficiency,and Soil Nutrient Dynamics of Summer Peanut (Arachis hypogaea L.) through Use of Polythene Mulch,Hydrogel, and Nutrient Management

Agronomic management through better use of inputs benefits farmers both by enhancing productivity and profitability. A field experiment was conducted in consecutive summer seasons (2011–2013) consisting of two mulching (no mulch, polythene mulch), three hydrogel (0, 2.5, 5.0 kg ha^?1), and three nutrient management treatments (organic, inorganic, and integrated) in a split–split plot design. Use of mulching and 2.5 kg hydrogel ha^?1 and integrated nutrient management enhanced pod, haulm, kernel and oil yields, and net economic returns. Partial factor productivity and water-use efficiency were higher under polythene mulch and 5.0 kg hydrogel ha^?1. Higher nutrient uptakes were obtained under both mulching and integrated nutrient management. Use of 2.5 kg hydrogel ha^?1 resulted in more removal of N; P and K uptakes were higher in 5.0 kg hydrogel ha^?1. Combination of three managements had a consequence of actual soil N loss, but gains in soil P and K after three cropping cycles.     

POTATO TUBER YIELD AND QUALITY AS AFFECTED BY RATES AND SOURCES OF POTASSIUM FERTILIZER

Among the major nutrients, potassium (K) not only improves yields but also improves quality parameters. Field experiments were conducted to assess the comparative effect of sources and rates of K fertilizer on potato yield and quality on a sandy loam soil. Graded doses of potassium, i.e., 0, 150 and 225 kg ha^?1 K₂O from sulfate and muriate of potash were applied in triplicate. Recommended dose of nitrogen (N) and phosphorus (P) applied uniformly. Significant increase in tuber yield was observed with 150 kg ha^?1 K₂O from both the sources over control. Increase in tuber yield with 225 kg ha^?1 K₂O was statistically non significant compared to 150 kg ha^?1. The dry matter and specific gravity were more affected with sulfate of potash (SOP) than muriate of potash (MOP). The quality parameters like dry matter, specific gravity, starch contents, vitamin C, chips color and taste were improved with K application.     

NITROGEN,PHOSPHORUS, AND POTASSIUM NUTRIENT EFFECTS ON GRAIN FILLING AND YIELD OF HIGH-YIELDING SUMMER CORN

A three-site-year field experiment was conducted to determine nitrogen (N), phosphorus (P), and potassium (K) fertilizer effects on grain filling dynamics and yield formation of high-yielding summer corn (Zea mays L.) in a wheat (Triticum aestivum L.)-corn double crop cropping system. Application of combined NPK fertilizers resulted in the greatest grain yield, largest grain number and grain weight when compared with the treatments receiving N, NP, or NK. Grain filling rate and duration, grain volume, and grain yield increased with NPK rates; however, doubling the rate of 180 kg N ha^?1, 40 kg P ha^?1, and 75 kg K ha^?1 fertilizer only led to minimal increases in grain filling rate (0.8%), grain filling duration (1.6%), grain volume (1.3%) and grain yield (0.4%). Our results suggested that for the high-yielding summer corn, a combined NPK fertilization is required to enhance grain filling and yield, and that under well-fertilized circumstances, limited increases in both grain filling and sink capacity might be the main factor restricting further yield improvement.     

Contribution of Biofertilizers and Fertilizer Nitrogen to Nutrient Uptake and Yield of Egyptian Winter Wheat

ABSTRACT

Nutrient uptake and grain and straw yield of Egyptian winter wheat (Triticum aestivum L. Merr.) were evaluated for two site-years after the seed inoculation with two biofertilizer products, Phosphorien, containing the phosphorus (P)-solubilizing bacteria Bacillus megatherium, and Nitrobien, containing a combination of nitrogen (N)-fixing bacteria Azotobacter chroococcum and Azospirillum liposerum. Ammonium nitrate and polymer-coated urea fertilizers were applied to plots alone and together with the biofertilizers at rates of either 83 kg N ha^?1 or 186 kg N ha^?1 for comparison. The highest grain yield (5.76–6.74 Mg ha^?1) and straw yield (11.49–13.32 Mg ha^?1) occurred at the highest fertilizer rates with N fertilizer. There was a slight additional increase in grain and straw yields when a biofertilizer was applied along with N fertilizer. A slightly higher grain and straw yield was measured with the polymer-coated urea treatment than with the ammonium nitrate treatment. The biofertilizer materials were not as effective as N fertilizers in producing grain (4.02–4.09 Mg ha^?1) or straw (7.71–8.11 Mg ha^?1) for either year, although the Nitrobien + Phosphorien combination increased these parameters over the N-fertilizer control. The effect of the Nitrobien biofertilizer in increasing grain yields was equivalent to a urea application rate of about 13 kg N ha^?1. Biofertilizer inoculations increased iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) concentrations in wheat tissue (at boot stage), but these higher levels did not influence grain or straw yield.     

System productivity,nutrient use efficiency and apparent nutrient balance in rice-based cropping systems

A 2-year field experiment was conducted to assess system productivity, nutrient use efficiency and apparent balances of phosphorus (P) and potassium (K) in diversified rice-based cropping systems at Gazipur, Bangladesh. Four cropping systems: wheat–fallow–rice, maize–fallow–rice, potato–fallow–rice and mustard–fallow–rice in main plots and four nutrient combinations: NPK, NK, NP and PK in sub-plots were arranged in a split-plot design with three replications. Receiving the NPK treatment, all the component crops gave the highest yield, and omission of N from fertilizer package gave the lowest yield. The maize–rice system removed the highest amount of N (217 kg ha^?1), P (41 kg ha^?1) and K (227 kg ha^?1) followed by wheat–rice, potato–rice and the least in mustard–rice system. The wheat–rice and maize–rice system showed negative K balance of –35.5 and –60.4 kg ha^?1 in NPK treatment, while potato–rice system showed a positive K balance of 31.0 kg ha^–1 with NPK treatment. The N, P and K uptake and apparent recovery by the test crops may be used for site-specific nutrient management. The K rates for fertilizer recommendation in wheat and maize in Indo-Gangetic plain need to be revised to take account for the negative K balance in soil.     

Alysimeter study of the effects of a ryegrass catch crop, during a winter wheat/maize rotation, on nitrate leaching and on the following crop

The effects of an intercrop catch crop (Italian ryegrass) on (i) the amounts and concentrations of nitrate leached during the autumn and winter intercrop period, and (ii) the following crop, were examined in a lysimeter experiment and compared with that from a bare fallow treatment. The catch crop was grown in a winter wheat/maize rotation, after harvest of the wheat, and incorporated into the soil before sowing the maize. A calcium and potassium nitrate fertilizer labelled with ¹⁵N (200 kg N ha^?1; 9.35 atom per cent excess) was applied to the winter wheat in spring. Total N uptake by the winter wheat was 154 kg ha^?1 and the recovery of fertilizer-derived N (labelled with ¹⁵N) was 60%. The catch crop (grown without further addition of N) yielded 3.8t ha^?1 herbage dry matter, containing 43 kg N ha^?1, of which 4.1 % was derived from the ¹⁵N-labelled fertilizer. Two-hundred kg unlabelled N ha^?1 was applied to the maize crop. During the intercrop period the nitrate concentration in water draining from the bare fallow lysimeters reached 68 mg N1^?1, with an average of 40 mg N1^?1. With the catch crop, it declined rapidly, from 41 mg N I^?1 to 0.25 mg N I^?1, at the end of ryegrass growth. Over this period, 110 kg N ha^?1 was leached under bare fallow, compared with 40 kg N ha^?1 under the catch crop. ¹⁵N-labelled nitrate was detected in the first drainage water collected in autumn, 5 months after the spring application. The quantity of fertilizer-N that was leached during this winter period was greater under bare fallow (18.7% of applied N) than when a catch crop was grown (7.1 %). In both treatments, labelled fertilizer-N contributed about 34% of the total N lost during this period. With the ryegrass catch crop incorporated at the time of seedbed preparation in spring, the subsequent maize grain-yield was lowered by an average of 13%. Total N-uptake by the maize sown following bare fallow was 224 kg N ha^?1, compared with 180 kg ha^?1 with prior incorporation of ryegrass; the corresponding values for uptake of residual labelled N were 3% (bare fallow) and 2% (ryegrass) of the initial application. Following the maize harvest, where ryegrass was incorporated, 22.7% of the previous year's labelled fertilizer addition was present in an organic form on the top 30 cm of lysimeter soil. This compares with 15.7% for the bare fallow intercropping treatment. Tracer analyses showed overall recoveries of labelled N of 91.7% for the winter wheat/ ryegrass/maize rotation and 97% for the winter wheat/bare fallow/maize rotation. The study clearly demonstrated the ecological importance of a catch crop in reducing N-leaching as well as its efficient use of fertilizer in the plant-soil system from this particular rotation. However, the fate of the organic N in the ploughed-down catch crop is uncertain and problems were encountered in establishing the next crop of maize.     

Yield,yield formation,and blackleg disease of oilseed rape cultivated in high-intensity crop rotations

The short-term economic benefit has in recent years prompted farmers to grow oilseed rape (OSR) (Brassica napus L.) and thus the frequency of this crop increased in German crop rotations. Here, we investigate the impact of high-intensity OSR crop rotations on yield, yield formation, and blackleg disease (Leptosphaeria maculans) in a rotation experiment in the Hercynian dry region of Central Germany over two seasons (2014/2015?–?2015/2016). The preceding crop combinations compared were winter wheat (WW) (Triticum aestivum L.)-WW, WW-OSR, OSR-OSR, and an OSR monoculture. Furthermore, the fertilizer treatments 120 kg N ha^?1 and 180 kg N ha^?1 were analyzed.

Higher OSR cropping intensity decreased seed yields, however, with a variation among years and oil yield was highest when OSR was following WW-WW over both years. Minor differences were observed among the yield components, but significantly less pods per m² were developed in a long-term OSR monoculture. The disease assessment clearly showed an increased blackleg incidence and severity when OSR was grown successively.

Results of our study emphasize that high-intensity OSR production will very likely be unsustainable over the long term associated with yield losses and increased infestation levels of blackleg disease.