Effects of nitrogen,boron and potassium on boron deficiency,leaf mineral concentrations,and yield of table beets (Beta vulgaris L.)

Abstract

Application of 11.2 kg B/ha and/or of 224 kg N/ha reduced the number of table beet (Beta vulgarisL. cv Detroit Dark Red) roots with B deficiency compared to low rates or no N or B application in three field experiments. In two of the three experiments, the 224 kg/ha N rate decreased B concentration in leaves when no B was added yet B deficiency of roots was reduced compared to the 56 kg/ha N rate. B application increased B concentration in leaves. Calcium concentration in leaves was higher at 224 kg N/ha than for 56 kg N/ha. Nitrogen concentration in leaves was increased by increasing the rate of N while K concentration was decreased at the higher N rate. Average number of roots with B deficiency was significantly higher for the Morse strain than for the Harris strain of ‘Detroit Dark Red’ in one experiment where the two strains were compared. There were no differences between the two strains in leaf B concentration but Ca concentration was higher in the Morse strain than for the Harris strain. Yields were higher at the 224 kg/ha rate of N than at 56 kg N/ha but were not consistently affected by B and K applications. There was no clear relationship of leaf N, Ca and K concentrations to B deficiency of roots     

Potassium,magnesium, and irrigation effects on peanuts grown on two soils

Abstract

Research data are limited on K and Wg requirements of peanuts (Arachis hypogaea L.) grown on sandy soils either with or without irrigation. Purposes of this study were (1) to determine Mg, K, and irrigation effects on yield, sound mature kernels (SMK's), and diseases of ‘Florunner’ peanuts grown on two sandy soils and (2) to determine sufficient amounts of Mg and K in peanut leaves and soils. Field experiments were conducted for three years on a Lakeland sand (thermic, coated Typic Quartzipsainments) and a Fuquay loamy sand (siliceous, thermic, Arenic Plinthic Paleudults). Both soils initially tested low in Mehlich 1 extractable K and Mg, but Lakeland was lower than Fuquay in both K and Mg. Factorial treatments were 0, 67, 67 (split into three applications), and 134 kg Mg/ha as MgS0₄ and 0, 56, 112, and 224 kg K/ha as KC1.

Neither irrigation, K, nor Mg treatment affected number of diseased plants. (Sclerotium rolfsii) or pod rot on either soil. Also, yield and % SMK's were not affected by any treatment any year on Fuquay soil. On Lakeland soil, yields were increased by irrigation 60.3% in 1980 and 11.0% in 1982, by K rates of 56 kg/ha or more each year, and by Mg rates of 67 kg/ha or more in 1978 and 1982. Yields (3‐yr average) were increased 14.7% by Mg with K and 30.7% by K with Mg. Magnesium plus K increased yields 69.3% over the control. Treatments had no consistent effects on % SMK's. Concentrations of K and Mg in leaves and soils were increased by increased rates of application but were not affected by irrigation. Minimum sufficiency levels for maximum yield were 10 and 2.0 g/kg for leaf K and Mg and 20 and 11 ng/kg for soil K and Mg (0 to 30 cm depth), respectively.     

Effect of fertilization and irrigation upon NPK composition of corn leaves,on corn yields,and available k in soil

Abstract

Corn (Zea mays L.) was grown for three consecutive years on Congaree loam to measure the effects of rates of N, P, and K fertilization and irrigation on the nutrient concentration of leaves, the level of available K in the soil, and on the yield of corn. Plant nutrients consisting of 0, 56, 140, 224, and 280 kg N/ha; 0, 15, 37.5, 60, and 75 kg P/ha, and 0, 28, 70, 112, and 140 kg K/ha were applied in a central composite rotatable design in each of the three years. All plant residue was removed each year when the corn was harvested, and the plots remained fallow during the winter months. One half of the experiment was irrigated when there was a 50% depletion of available soil moisture in the 0‐ to 46‐cm soil depth.

Leaf composition was affected by fertilization and irrigation. A rapid decrease in available soil K in the 0‐ to 15‐cm depth was evident the first year with all rates of added K. The decline in available soil K was unaffected by irrigation and levels of applied N and P.

There were consistent yield responses each year to added N, no response to added P, and a response to added K only during the second year.     

Dry matter yield and nitrogen recovery from bromegrass in south‐central Alberta as affected by rate of long‐term nitrogen applications

Abstract

A field experiment was conducted on a Thin Black Chemozemic soil at Crossfield in south‐central Alberta to determine the effect of long‐term application of ammonium nitrate on dry matter yield (DMY), protein yield (PY), protein concentration, N use efficiency and recovery of N applied to bromegrass (Bromus inermis Leyss.) grown for hay. The N fertilizer was applied at 0, 56, 112, 168, 224, 280, and 336 kg N/ha in early spring of every year from 1968 to 1986. The DMY increased with applied N achieving a maximum at 224 kg N/ha, though the rate of increase in DMY from N fertilization was greatest with the first two increments applied (i.e. 56 and 112 kg N/ha). Protein yield and protein concentration maximized at 336 kg N/ha. The DMY was greater with a single‐cut system than with a double‐cut system. The DMY varied from year to year, but it was not closely related to precipitation received during the April to August period (R² = 0.37). However, in some years low DMYs were associated with low precipitation, or a lack of timeliness of rainfall, or a combination of both. The N use efficiency and % N recovery in bromegrass decreased with increasing N rate. The maximum DMY calculated from quadratic regressions ranged from 3.16 t/ha to 7.91 t/ha, and maximum N rate ranged from 205 to 258 kg N/ha. In summary, DMY, PY, and protein concentration increased, and N use efficiency and % N recovery decreased with increasing N rate in this 19‐year study.     

Stand recovery of coastal bermudagrass following stand loss induced by potassium deficiency

Abstract

‘Coastal’ bermudagrass (Cynodon dactylon L. Pers.) stand loss resulting from K deficiency has been reported. The recovery of this perennial grass from K deficiency could very well take a significant time after the deficiency is corrected. Experiments were conducted on two soils, Darco (Grossarenic Paleudult; loamy, siliceous, thermic) and Cuthbert (Typic Hapludult; clayey, mixed, thermic). Previous P and K factorial rate studies had been conducted on the experimental sites. Annual K and P fertility rates used on prior studies were 0, 112, and 224 kg/ha K and 0 to 136 kg/ha P. These earlier treatments were overlaid with rates of 112 and 224 kg/ha of P and K, respectively. Data were taken for yield, stem length, stem weight, and rhizome production. Yield was found to be related directly to stand. Yield was also related to plant height under severe stand loss. Yield loss was not related to stem weight. Rhizome production recovered after two years. Yield had recovered by the end of the first year.     

Effects of nitrogen,phosphorus, and potassium nutrition on yield,rates of kernel growth and grain filling periods of two corn hybrids

Abstract

Depression of corn grain yields from nutrient stress has been studied extensively, but effects of nutrient stress on rates of corn development and yield determinants are less well understood. Nutritional effects on the number of kernels/unit area, growth rate/kernel, and duration of growth have implications concerning fertilization practices and yield potentials of crops. Two corn hybrids with equivalent silking dates but having different grain filling periods were grown in a field experiment. Fertility treatments consisted of a N series receiving 0, 112, or 336 kg of N/ha and a P‐K series receiving factorial combinations of 0, 22, or 112 kg of P/ha and 0, 56, or 224 kg of K/ha. Dates for grain initiation and maturity were determined for each plot along with tissue analyses of ear leaves, grain yields, and kernel weights. Concentrations of N and K in ear leaves generally corresponded to treatment levels of these nutrients, although Pioneer Hi‐bred 3390 appeared to be less efficient than Pioneer Hi‐bred 3334 in K uptake. Effects of nutrient stress on yield determinants depended on the determinant and nutrient under consideration. Severe N stress did not change length of grain filling periods, but decreased kernel numbers 30 to 70%. Stress for K, on the other hand, shortened grain filling periods about 13% and had only a slight effect on kernel number. Negligible P stress occurred in the experiment. The two hybrids produced equal quantities of grain/ha/day but the hybrid with a longer filling period (Pioneer 3334) filled many more kernels at a slightly slower rate and for a longer period of time to give a significantly greater grain yield compared to Pioneer 3390.     

Response of maize to nitrogen,phosphorus, and potassium fertilizers in the savanna zones of Nigeria

Abstract

Field trials were conducted for three years on the response of maize to nitrogen (N), phosphorus (P), and potassium (K) fertilizers on Oyo Soil Series (Arenic Haplustalf) and Iregun series (Aquic Haplustalf) in the derived savanna and southern guinea savanna zones of Nigeria, respectively. Nitrogen fertilizer as granulated urea at rates 0–300 kg N/ha, P fertilizer as single superphosphate at rates 0–120 kg P/h, and K fertilizer as muriate of potash at rates 0–180 kg K/ha were used for the different nutrient combinations. The base rates for N, P, and K were 100 kg N/ha, 40 kg P/ha, and 60 kg K/ha, respectively. The results of the trials showed that annual application of the blanket recommended N, P, and K rates to maize grown under intensive land use system could not produce optimum yield. Fertilizer efficiency varied along with soil test values from year to year. The highest response by maize in these zones was to N, the optimum rate ranged from 50–100 kg N/ha. Application of high rates of P and K fertilizers on soils with fairly sufficient nutrient level showed no significant effect on maize yield. But when P and K were applied at low rates (20 kg P/ha and 30 kg K/ha), their contents in the leaf and maize yield, in most cases, increased significantly. The results, however, showed that N, P, and K recommendations for optimum maize yield in both zones are 50–100 kg N/ha, 20 kg P/ha, and 0–30 kg K/ha, respectively.     

Soil chemical properties after long‐term n fertilization of bromegrass: Nitrogen rate

Abstract

Nitrogen (N) fertilizers increase yield and quality of grass forage, and may also alter soil chemical properties. A field experiment was conducted in south‐central Alberta to determine the effect of long‐term application of ammonium nitrate to bromegrass on concentration and downward mobility of soluble NO₃‐N, extractable NH₄‐N, P, Ca, Mg, and K, and total C and N in a Thin Black Chernozemic loam soil. The fertilizer was applied annually in early spring for 16 years at 0 to 336 kg N/ha. There was little accumulation of NO₃‐N in the soil at N rates of 112 kg/ha or less. However, at rates higher than 112 kg N/ha there was accumulation of NO₃‐N in the 15–30 and 30–60 cm layers, but very little in the 90–120 cm depth. The NH₄‐N accumulated in the 0–5 cm layer when the fertilizer was applied at rates between 168 to 280 kg N/ha and in the 5–10 cm layer at N rates exceeding 280 kg/ha. There was a decline in extractable P in soil with N application up to 84 kg N/ha rate, while it increased with high N rates. The increasing amounts of applied N resulted in a decline in extractable soil Ca, Mg and K, and this decrease was more pronounced in the 0–5,5–10,10–15, and 15–30 cm layers for K, 0–5 and 5–10 cm layers for Ca, and 0–5, 5–10, and 10–15 cm layers for Mg. There was a build‐up of total C and N in the surface soil with increasing rate of applied N.     

Rabbiteye blueberry plant response to nitrogen and phosphorus

Acid, sandy soils selected for blueberry production are usually deficient in plant available phosphorus. Fertilizer addition at planting has not been a recommended practice. This research was designed to evaluate potted blueberry (Vaccinium ashei Reade) plant growth response to P applied at establishment and interacted with N applied during the growing season. Four liter containerized ‘Tifblue’ rabbiteye blueberry plants were transplanted into 4.4 kg of 1:1 v/v loamy sand:peat mixture in an 8‐liter container. Preplant P was incorporated into the mixture at 0, 20, 40, 60, and 80 kg/ha rates. Nitrogen was split‐applied post‐plant four times at 60‐day intervals beginning 30 days after blueberry bushes were transplanted. Total N rates were equivalent to 0, 112, 224, or 336 kg/ha. Plants were harvested 270 days after transplanting. Phosphorus at the 60 and 80 kg/ha rates increased plant growth 40 and 31%, respectively. Plant growth responded linearly to increasing N rate. Leaf and stem weight increases contributed to this linear response while root weight was not affected by fertilizer N. Total plant dry weight was increased by N rates at the 60 and 80 kg/ha P levels. Phosphorus applications increased leaf P levels, but did not increase soil test P. Leaf redness, caused by cool temperatures, was reduced by high N rates. The optimum P rate for fertilization of the soilrpeat mixture in the planting hole under conditions of this experiment was the equivalent of 60 kg/ha.     

Effect of nitrogen rate,nitrogen timing,and nitrification inhibitors on grain sorghum production in Arkansas

Abstract

Nitrogen efficiency may be improved in grain sorghum [Sorghum bicolor (L.) Moench.] production by using the optimum N rate, splitting the N applications, and by the use of nitrification inhibitors. Nitrogen rates of 0, 56, 112, 168, and 224 kg N/ha with and without nitrification inhibitors, dicyandiamide (DCD) and nitrapyrin, were evaluated in 1985 and 1986 at two locations in Arkansas. Selected N rates were evaluated when applied all preplant and when the applications were split. In 1986, at one location, two N rates (0 and 168 kg N/ha), DCD and nitrapyrin, and different times of N application were evaluated. These treatments were evaluated at two soil water deficits, 2 and 4 cm. The soils were a poorly drained Sharkey sc (Vertic Haplaquept) in northern Arkansas and moderately well drained Hebert sl (Aeric Ochraqualf) in southern Arkansas. Maximum grain sorghum yield occurred at a lower N rate on the silt loam soil than on the clayey soil in both years of the study. Based on soil inorganic N, the DCD nitrification inhibitor tended to inhibit nitrification during the early growing season on the Sharkey sc. However, the inhibitors did not affect the soil inorganic N on the Hebert sl. Grain yield and plant N were not increased by the inhibitors in any of the studies. Grain yield was not increased by the split N application treatment compared to the preplant N application. However, split N applications increased plant N above the preplant application under high soil moisture conditions.     

Yield and protein quality of five soft red winter wheat cultivars as affected by nitrogen fertilization rate

Abstract

This study reports the relationship between N levels (22, 56 and 112 kg/ha) and its effect on yield and protein quality for five cultivars of soft winter wheat (Triticum aestivum L. em. Thell). The objective was to determine the relationship of amino acid content and total protein at various levels of N. The 56 and 112 kg N/ha rates resulted in higher wheat yields than the 22 kg N rate over the 3 yr. mean. A cultivar x N level interaction for yield occurred when certain cultivars did not respond to higher N rates in 1972. Total seed protein increased with each increase in If. Increasing N levels generally resulted in a higher amlno acid content of the seed. Cultivar effects were found for 6 of the 17 amino acids (threonine, serine, glutamic acid, proline, glycine and lysine) indicating that cultivars differed in total amino acid content. Cultivars Arthur and Holley gave the greatest response (percentage amino acid) to N application. Coker 68–8 was intermediate in response while Coker 68–15 and Blueboy showed small inconsistent responses to H application.     

Response of tall fescue to fertilizer placement at different levels of phosphorus,potassium, and soil pH 1

Fertilizer application, particularly nitrogen (N), is important in cool‐season grass forage production. Subsurface (knife) placement of N often has resulted in higher forage yield and N uptake of tall fescue (Festuca arundinacea Schreb.) compared to surface‐broadcast fertilization, but further studies were needed to indicate whether soil pH, phosphorus (P), or potassium (K) modifies the response. Experiment I tested responses of forage yield and N and P concentration to N, P, and K amount and placement. Two types of fertilizer placement ‐ broadcast and knife ‐ were used with 13, 112, or 168 kg N; 0 or 19 kg P; and 0 or 37 kg K/ha in a factorial arrangement. Yields increased by 53% as N fertilization went from 13 to 112 kg/ha and by 69% as N increased from 13 to 168 kg N/ha. Forage yield was increased 26% from knife compared to broadcast fertilizer placement. P application increased forage production by 13%, but K application had no effect on yield. Forage N concentrations increased by 25% as N fertilization went from 13 to 112 kg/ha and by 38% as N increased from 13 to 168 kg N/ha. Effects of added P and fertilizer placement on N concentration often resulted in interactions among factors. Forage P generally was increased by added P, with some effects of interactions among N rate, P rate, and placement. In Experiment II, fescue responses to N placement were tested where different soil characteristics had been established by previous lime and fertility treatments. Forage yield, N concentration, and N uptake were highest where 9.36 Mg/ha of lime were applied as compared to the control. Previous fertility treatments had no significant (P<0.05) effect. When N was knifed, forage yield was related positively to available soil P but not to pH or K. Yield and forage N concentration and uptake were increased by 20, 11, and 33%, respectively, as a result of knife versus broadcast N application.     

Effect of B,Mn and Zn on nodulation and N2‐fixation in southernpeas

Abstract

Two greenhouse studies were conducted to evaluate the effect of B, Mn and Zn on nodulation and N₂‐fixation of southernpea (Vigna unguiculata (L.) Halp.) cultivars ‘Freezegreen’, ‘Mississippi Silver’ and ‘Pinkeye Purple Hull’. The cultivars were grown in plastic pots with a Norfolk sandy loam (fine, loamy siliceous thermic, Typic Paleudult) soil treated with B, Mn and Zn at rates of 0, 5, 10 and 20 kg/ha each at pH levels 5.5, 6.0 and 6.5. At pH 6.5 all micronutrient treatments significantly increased nodulation and N₂‐fixation over the control (no micronutrient applied). The effects of B, Mn and Zn on nodulation and N₂‐fixation depended on the cultivar and soil pH. For plants given the 5 kg/ha B and Mn treatments, ‘Mississippi Silver’ produced the highest number of nodules and ‘Pinkeye Purple Hull’ the least. At 20 kg/ha Zn, nodulation of ‘Freezegreen’ was highest and ‘Pinkeye Purple Hull’ the lowest. As a whole, maximum nodulation was at 5 kg/ha B and Mn and 20 kg/ha for Zn. Nitrogen fixation rates responded similarly except that the optimum rate for Zn was 10 kg/ha. Seed yield of plants peaked at 5 kg/ha for B and 10 kg/ha for Zn, indicating a possible relation of N₂‐fixation to seed yield.     

Effect of magnesium fertilization on yield and leaf composition of tomato plants

Tomato plants were grown for 2 years at 4 different rates of Mg fertilization on a Princeton loamy sand at pH 4.8 with 29 kg exchangeable Mg/ha. Calcareous limestone was used to provide a pH treatment in the second year. Magnesium deficiency symptoms were observed on plants grown on plots having ≤ 38 kg/ha NH₄OAC‐extractable Mg. Application of 56 kg Mg/ha corrected Mg deficiency and produced a significant increase in yield. Application of calcitic limestone also produced significant yield increases, but did not affect the development of Mg deficiency symptoms. Tomato yield was increased 27.9% by Mg application and 17.7% by lime application. Highest tomato yield was obtained with application of 112 kg Mg/ha. Symptoms of Mg deficiency were observed when the Mg concentration in recently mature leaf tissue was in the 0.30 to 0.32% range. Magnesium concentration in leaf tissue increased linearly with increasing Mg rate. Leaf Mg concentration at various growth stages of the tomato plant was variable depending on Mg treatment. Magnesium fertilization rate bad little effect on Ca or K leaf concentrations. Application of Calcltic limestone increased leaf tissue Ca and reduced leaf tissue Mg and Mn concentrations.     

Potassium and Nitrogen Distribution Pattern and Growth of Flue-Cured Tobacco Seedlings Influenced by Nitrogen Form and Calcium Carbonate in Hydroponic Culture

ABSTRACT

Grape tomatoes (Solanum lycopersicon L. var. cerasiform) have recently gained in popularity among consumers because they can be eaten without being cut, they are deep red in color, and their flavor is intense and pleasant. Current nitrogen (N) fertilization recommendations were developed for determinate tomato varieties that have a 3-month long growing season, whereas that of the indeterminate grape cultivars may be up to six months. ‘Tami G’ grape tomatoes were grown on a Lakeland fine sand at the North Florida Research and Education Center—Suwannee Valley, near Live Oak, FL in Springs 2005 and 2006 using standard plasticulture practices under 0%, 33%, 66%, 100%, 133%, and 166% of the current recommended N rate for round tomato (224 kg/ha). Due to a longer growing season in 2006, plants received an additional three weekly injections of 22 kg/ha of N each in the 100% rate, that were also proportionally applied to the other treatments. Tomatoes were transplanted March 24, 2005 and April 4, 2006 and harvested, weighed and graded five (2005) and seven (2006) times. Season marketable yield (SMY) responses to N rates were quadratic (both years P < 0.01) and highest SMY (40,340 and 36,873 kg/ha) occurred with 314 and 280 kg/ha of N in 2005 and 2006, respectively. Fruit soluble solids concentrations ranged from 6.25 to 7.5, and 7.0 to 8.3° Brix in 2005 and 2006, respectively, and were not significantly affected by N rate. These results suggest that N fertilization for grape tomato grown in Spring with plasticulture could be done by incorporating 56 kg/ha of N in the bed, followed by daily rates ranging from 0.5 to 3.5 kg/ha/day. Because the length of the growing season for grape tomato may vary, emphasis should be placed on daily N rates and irrigation management, rather than on seasonal N rate.     

Tomato response to long‐term potassium and lime application on a sandy ultisol high in non‐exchangeable potassium

In a ten‐year study of potassium (K) and lime application to a Kalmia sandy loam (fine‐loamy, siliceous, thermic Typic Hapludult), a soil high in nonexchangeable K, corn (Zea mays L.) and soybean [Glycine max (L.) Herr.] have not responded to applied K. The objectives of this study were to determine if a high K‐requiring crop such as tomato (Lycocersicon esculentum Mill. cv. Redpak) would respond to KCl fertilizer rate or lime type (dolomitic, calcitic, and mixed) and rate on such a soil. Potassium was applied at 0, 56, and 112 kg K/ha every year for ten years. Lime was applied at 0, 2, and 9 Mg/ha in calcitic, mixed, and dolomitic forms twice in ten years (1970 and 1973). In 1980, the tenth year of the study, tomato fruit was harvested by hand once‐over to simulate machine harvest and divided into four maturity groups by color. Soil pH was higher with dolomitic than calcitic lime. Soil K saturation was not influenced by lime rate or type. Fruit yield and leaf phosphorus (P), calcium (Ca), and magnesium (Mg) concentrations increased with increasing lime rates. Leaf K, manganese (Mn), iron (Fe), boron (B), copper (Cu), zinc (Zn), barium (Ba), strontium (Sr), and aluminum (Al) concentrations decreased with increasing lime rate. Leaf Mn, Ba, and Sr concentrations were lower with dolomitic than with calcitic lime. Lime type had no effect on tomato yield. Wide ranges in basic cation saturation ratios had little effect on yield. Soil K saturation and leaf K, Zn, and Ba concentrations increased with increasing K rate. Soil Ca and leaf Ca, Mg, and Al concentrations decreased with increasing K rate. Applied K had no effect on total yield but onceover marketable yield increased linearly with increasing K rate. Marketable yield increased 14% with an increase in K rate from 0 to 56 kg/ha. Thus, fruit maturity was apparently hastened by K fertilization.     

Yield response of corn to lime and urea application on an acidic tropical soil

Abstract

The effects of liming (7 500 kg CaCO₃/ha) and rate of urea application (0,50,100, and 200 kg N/ha) and its placement at the surface or at 5 cm depth on grain yield and nutrient uptake by corn grown on an acidic tropical soil (Fluventic Eutropept) were studied. Liming significantly increased grain yield, N uptake, and P and K uptake although Ca and Mg uptake, generally, were unaffected. Sub‐surface application of urea increased N uptake only. Yield response to applied N was observed up to 50 kg N/ha when limed but at all rates in the absence of liming. It therefore, reduced the fertilizer N requirement for optimum grain yield. Liming the acidic soil also reduced exchangeable Al but increased nitrification rate and available P in the soil profile (at least up to 0.6 m depth).     

Effect on N P K applications on potatoes grown on a well decomposed and intensively fertilized organic soil

Abstract

Using predictably excessive rates of N, P and K for potatoes on a well decomposed and intensively fertilized organic soil, it was observed that while N depressed yields somewhat, there were neither deleterious nor beneficial effects from the application of P or K. The highest rates of P and K used were 1792 and 3584 kg/ha respectively. Increasing rates of N decreased B concentrations in the potato leaf tissue while increasing rate of K resulted in increasing concentrations of B. Zinc tended to be higher in leaf tissue as excessive phosphorus application rates increased.     

Nitrogen efficiency of grain sorghum grown on flat and raised seedbeds on poorly drained soil

Grain sorghum (Sorghum bicolor L. Moench) production commonly occurs on poorly drained clayey soils of the Mississippi River delta region inArkansas. Raised, wide seedbeds may improve grain yield and fertilizer N efficiency for narrow‐row sorghum production on these soils. The influence of individual row positions on raised, wide seedbeds was compared to conventional flat seedbed for grain yield, yield components, dry weight, and N uptake. A 193‐cm wide and 15 cm high crowned seedbed (CB) was compared to the flat seedbed (FB) in 1987 and 1988 on a Sharkey silty clay (very fine, mont‐morillonitic, nonacid, thermic, Vertic Haplaquepts) at Keiser, AR. Three rows were planted on each seedbed treatment; one in the middle of the bed and one row 48 cm to each side of the row in the middle. Nitrogen rates of 0, 56, 112, and 168 kg/ha were applied at planting. In addition, two split applications at the 168 kg/ha N rate (56 kg N/ha at planting and 112 kg N/ha at either four‐leaf or eight‐leaf growth stage) were evaluated. Each row position was evaluated for grain yield, yield components, plant dry weight, and N uptake. Whole plant samples were collected at the anthesis and physiological maturity growth stages. The field average grain yield was higher on the CB each year regardless of N rate applied at planting. This yield increase on the CB was related to the row on the top of the CB yielding more than the equivalent row on the FB. The responses of plant dry weight at each growth stage, N uptake at each growth stage, and N content of the seed was similar to grain yield responses. The split N application at planting and the eight‐leaf growth stage was as effective or better than any other treatment for increasing grain yield, N uptake, and seed N content.     

Effect of nitrogen,phosphorus and potassium on yields,protein cohtents and otrient levels in soybeans,field peas and fababeans

Abstract

Soybeans, Glycine max (L.) Merr., field peas, Plsum sativum I., and fababeans, Vicia faba L., were each grown at either three or four locations. Fertilizer treatments consisted of three rates of N, three of P and three of K applied in all possible combinations.

In general fertilizers had minimal effects on yields and on the percentages of N, P, K, Ca and Mg in leaf tissue. The most consistent effect was a decrease in leaf Mg with application of increasing; rates of K.

Average yields at different locations ranged from 1735–2997 kg/ha for soybeans, 2940–3246 kg/ha for field peas and 1569—4435 kg/ha for fababeans. The results suggest, however, that factors other than soil chemical properties probably had an appreciable effect on yields.