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1.
Upland rice is an important crop in South America, including Brazil. Nutrient interactions are important in determining crop yields. A greenhouse experiment was conducted to evaluate interaction among nitrogen (N), phosphorus (P), and potassium (K) in upland rice production. The treatments applied to upland rice grown on an Oxisol were three levels of N (N0, N150 and N300 mg kg?1), three levels of P (P0, P100 and P200 mg kg?1) and three levels of K (K0, K100 and K200 mg kg?1). These treatments were tested in a 3 × 3 × 3 factorial arrangement. Grain yield, shoot dry weight, plant height, root dry weight, maximum root length, panicle number, 1000-grain weight, and grain harvest index were significantly influenced by N, P, and K treatments. The treatment that did not receive P fertilization did not produce panicle or grain. Hence, P was most yield-limiting nutrient compared to two other nutrients. At the N0P0K0 treatment, rice did not produce grains, indicating severe deficiency of these nutrients in Brazilian Oxisols. Maximum grain yield was obtained with the N300P200K200 treatment. Grain yield had significant positive association with plant height, shoot dry weight, root dry weight, maximum root length, 1000-grain weight, panicle number, and grain harvest index. Among these growth and yield components, shoot dry weight had the highest positive association with grain yield and root length minimum positive association with grain yield. Hence, adopting adequate soil and crop management practices can improve growth and yield components and increase grain yield of upland rice.  相似文献   

2.
Neglected P and K fertilization in organic farming reduces N2 fixation and grain yield in a red clover‐oat rotation N2 fixation is the most important N source in organic farming. An insufficient P, K, and S supply to legumes may reduce their N2 fixation capacity. Consequently, the total yield of plant production may also be reduced. This problem was studied in a pot experiment with red clover followed by oat. Soil was taken from a field where organic farming had been practiced for more than 30 years without applying any mineral fertilizers or buying additional fodder. The soil (luvisol from loess) was characterized by: pH (CaCl2) 5.4; lactate‐soluble (CAL) P 5 mg kg–1 and K 110 mg kg–1. 6 kg dry soil were mixed with 400 mg P applied as (i) triplesuperphosphate (TSP), (ii) rock phosphate (RP) or (iii) compost from organic household residues (BAK). An additional treatment (iv) with TSP received 1000 mg K as K2SO4 (TSP+K) and an additional treatment with RP (v) received only 200 mg P (RP/2). A control treatment received no fertilizer. P application significantly improved the P nutritional status of the plants (P content) and increased the N amount in the shoots of red clover (with 400 mg P per pot by 64 % to 139 % as compared to the control) and the dry matter (DM) yield by 60 % to 130 %. No significant differences between TSP and RP were found. The application of BAK resulted in a significantly higher N yield than the application of RP and TSP. The treatment TSP+K resulted in the highest DM yield (230 %), removal of P was 343 %, of K 228 %, and of N 239 % as compared to the control plants. This indicates a synergistic effect of P, K, and S on N2 fixation, which was also found with BAK. Oat grown after red clover increased its grain yield by 132 % (200 mg P as RP) to 165 % (400 mg P treatments). This was mainly due to a higher P uptake (up to 172 %) and a higher N uptake (up to 172 %) as compared to the control.  相似文献   

3.
Soil specific maize response to N and P may provide guidelines for improving nutrient management. Three replicates of N and P fertilizer combinations (N0P0, N0P90, N120P0, and N120P90) were arranged in randomized complete block design on Plinthic Acrisol (PA) and Gleyic Plinthic Acrisol (GPA) in Ghana. Treatment effects on maize plant height and yield parameters were assessed. Plant height differed consistently with N120P90 > N0P90 > N120P0/N0P0 from 3 to 7?weeks after planting on the GPA. On the GPA, grain yield ranged from 1.20 to 2.40 t ha?1 and increased by 10, 77 and 95% in the N120P0, N0P90 and N120P90, respectively. Residual effect of N0P90 and N120P90 increased maize yields on the GPA than on the PA. Rather than N, P was more critical to maize performance and should be externally supplied not exceeding the critical level of N0P60 (Plinthic Acrisol) and N0P90 (Gleyic Plinthic Acrisol) for optimum maize yield.  相似文献   

4.
Dairy manure (DM) rates of [0 (DM0), 30 (DM30)), 60 (DM60) Mg ha?1] and three nitrogen (N) rates [0 (N0), 125 (N125), 250 (N250) kg ha?1] were tested in a sandy clay loam, to evaluate their effects on growth and yield of wheat crop (Triticum aestivum L.), residual nitrate nitrogen (NO3-N) and phosphorus (P) concentrations in the surface soil, and selected soil physical measurements [saturated hydraulic conductivity (Ksat), and bulk density (BD)]. Increasing N and DM rates gave higher wheat yields, increased concentrations of residual NO3-N and P in the surface soil and improved Ksat and BD. Highest grain yield of 3.8 Mg ha?1 (70.3% more than the control) was observed in DM60 × N250 treatment. Residual accumulation of N-NO3 and P in the surface soil at high N and/or DM application rates suggests the need to carefully manage N and DM inputs on farm fields to avoid environmental contamination.  相似文献   

5.
氮磷用量对豫北地区小麦产量的交互效应研究   总被引：2，自引：2，他引：0  
采用盆栽试验研究了氮磷不同用量与配比对小麦产量的影响,分析了产量与小麦不同生育期各生理指标之间的关系。结果表明:氮磷施用存在最佳配比,当氮磷肥用量分别相当于220kg(N)·hm-2和160kg(P2O5)·hm-2时,小麦产量最高。小麦产量与根系活力、开花期酸性磷酸酶活性和拔节期硝酸还原酶活性密切相关,根系活力、酸性磷酸酶和硝酸还原酶活性与小麦吸收的氮磷总量呈显著正相关关系。根系活力、酸性磷酸酶和硝酸还原酶活性随着磷肥用量增加而提高,随着氮肥用量增加先提高后下降,因此过多的氮肥施用通过降低小麦根系活力、酸性磷酸酶和硝酸还原酶活性等,减少小麦对氮磷吸收,进而降低产量。  相似文献   

6.
The performance of Sesbania rostrata varies widely from site to site. This makes it difficult to predict the N yield and biomass of this plant in marginally productive soils, and to arouse the interest of farmers in green manure technology. Three consecutive pot experiments were conducted in a greenhouse at the International Rice Research Institute (IRRI) to evaluate growth, nodulation, N2 fixation (C2H2 reduction assay and 15N dilution method), and N yield of 6-week-old S. rostrata on 13 physicochemically different wetland rice soils of the Philippines and on three artificial substrates. The performance of S. rostrata on the unfertilized controls was compared with two fertilizer treatments containing either P (100 mg P kg-1 dry soil) or P+K (100 mg P kg-1 and 200 mg K kg-1 dry soil). In the control soils and substrates, the N yield of S. rostrata varied between 20 and 470 mg N per pot, with the N rate from N2 fixation ranging between 0 and 95%. In three of the nutritionally poor soils even Mn toxicity symptoms apparently occurred with S. rostrata. P application alleviated these symptoms and increased the overall N yield considerably, mainly through increased biological N2 fixation. An additional increase in N yield was obtained by the PK treatment. Multiple regression analysis between soil characteristics and the N yield of S. rostrata showed that the original level of P (Olsen-extracted) and Mn in the soil accounted for 73% of the variance in biomass production by S. rostrata among the unfertilized soils and substrates.  相似文献   

7.
A field experiment was conducted in continuity of our previous study to assess the effect of Rhizobium inoculation (RI) and phosphorus fertilization (P) on growth, yield, nodulation, and P use efficiency of soybean. Different treatments were i) Rhizobium strains (0, S377, S379, and the mixture of S377+S379 i.e. S0, S1, S2, S3); ii) phosphorus fertilizer (0, 50, 100 kg ha?1 i.e. P0, P1, P2). Soybean variety NARC-1 was as used as a testing crop. Results indicated that root and shoot growth increased by RI treatments whether used alone or in combination with P. Rhizobium inoculation increased plant height up to 12% while P did not show significant effect. Increases in soot dry weight, root length and root dry weight due to RI and P was 57 and 22%, 42 and 7%, 55 and 25%, respectively, over the control treatment. Number of nodules increased from 73 in the control to a maximum of 151 in S2 while the number increased from 90 in the control to 147 in P2. Combine application of strains and P increased nodules number from 65 at S0P0 to a maximum of 183 at S2P2. Similar response was also observed for nodules mass. Soybean seed yields ranged between 1710 and 2335 kg ha?1 against 1635 kg ha?1 in the control indicating a maximum of 43% increase over control. Concentration of N and P in plants and their uptake was significantly increased by RI and P. RI also increased the N and protein content of soybean seed. Apparent recovery efficiency (ARE) of applied P was 10?12% and the agronomic, agrophysiological, recovery, utilization efficiencies, and harvest index of P decreased with increasing P rates. Nodule number significantly correlated with the DM yield (r2 = 0.78) and seed yield (r2 = 0.63) while P uptake significantly correlated with root length (r2 = 0.48) and root mass i.e. dry weight (r2 = 0.65). Also a significant correlation existed between N uptake and DM yield (r2 = 0.98) and N uptake and seed yield (r2 = 0.65), P uptake and DM yield (r2 = 0.73), and P uptake and seed yield (r2 = 0.83). The results of present study indicated a substantial growth and yield potential of soybean under the hilly region and increase in yield and N2 fixing potential (nodulation) can be achieved by applying Rhizobium inoculation with P fertilization.  相似文献   

8.
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.  相似文献   

9.
In a long‐term maize–wheat rotation at the Punjab Agricultural University, Ludhiana, India (subtropical climate), the effects of nitrogen (N), phosphorus (P), and potassium (K) addition on soil fertility and forms of inorganic P and K in the plow layer of an alkaline sandy loam soil were measured after 11 and 22 years of cropping. The treatments comprised four rates of N (0, 60, 120, and 180 kg N ha?1) as urea, three rates of P (0, 17.5, and 35 kg P ha?1) as single superphosphate, and two rates of K (0 and 33 kg K ha?1) as muriate of potash. The treatments selected for the present study were N0P0K0, N120P0K0, N120P17.5K0, N120P35K0, N120P17.5K33, and N120P35K33. A significant year × treatment interaction in decreasing available N [alkaline potassium permanganate (KMnO4)–oxidizable N) status of soils was found in all the treatments. Available P (Olsen P) in the control plot decreased over time whereas in plots with added P, available P increased significantly after years 11 and 22, with the greatest increase in the N120P17.5Ko treatment. Compared to the initial values, continuous P fertilization resulted in greater total P and chloride P concentrations after 11 and 22 years. Although sodium hydroxide (NaOH) P and sulfuric acid (H2SO4) P increased in P‐treated plots from the start of the trial to year 11, they decreased from year 11 to year 22. Among these inorganic P forms, chloride P was significantly positively correlated with P uptake (r = 0.811*). When only N and P were applied, available K [ammonium acetate (NH4OAc)–extractable K] significantly decreased over time. In plots without K addition, water‐soluble and exchangeable K decreased from their initial status. Compared to year 11, water‐soluble K increased, whereas exchangeable K decreased after year 22 in plots receiving no K fertilizer. Compared with NPK treatments, a significant decrease of total K in NP treatment plots suggests the release and uptake of nonexchangeable K. Water‐soluble K and exchangeable K were not correlated with K uptake. These results suggest that long‐term application of P fertilizers resulted in the accumulation of P in the soil, which could have resulted in saturation of P binding sites. Of the soil inorganic P fractions, only chloride P appears to be a good indicator of plant‐available P. The gradual loss in native soil K and release of nonexchangeable K indicates the need for adding K fertilizer to maintain soil fertility.  相似文献   

10.
Abstract

Despite being a major domain of global food supply, rice–wheat (RW) cropping system is questioned for its contribution to biomass burning in Indo-Gangetic Plains (IGP). Enhancing the yield and soil quality properties in this system is therefore necessary to reduce environmental degradation and maintain agricultural productivity. A field experiment evaluated the effects of soil management practices such as rice residue (RS) incorporation, and nitrogen (N) application on crop yield and micronutrients transformations in a RW cropping system of north-western India. The results revealed that N application (120?kg N ha?1) and RS incorporation (7.5 t ha?1) significantly increased micronutrients cations and crop yield compared with no-residue (RS0). Irrespective of N application, crop grain yield under RS incorporation (Rs7.5 t ha?1) was significantly higher than RS0 incorporation. Significant increase in all the micronutrient transformations was recorded in N120/Rs7.5 t ha?1 compared with RS0. Among different fractions, crystalline Fe bound in Zn, Mn, and Cu and amorphous Fe oxide in Fe fractions were the dominant fractions under N application (N120) and RS incorporation (RS7.5) treatment. Our study showed that application of N120 followed by RS7.5 can be more sustainable practice under RW cropping system for improvement in micronutrients availability and crop yield. This practice also provides an opportunity to incorporation of crop residues as an alternative to burning, which causes severe air pollution in the RW cropping system in the IGP.  相似文献   

11.
Abstract

An experiment was conducted in a semi‐arid region located in the State of Zulia, western part of Venezuela (10°32'N and 71°42'W, 600 mm average annual rainfall), to evaluate dry matter (DM) yield and in vitro organic matter digestibility (IVOMD), and crude protein (CP) content of Andropogon gayanus Kunth as affected by three frequencies of defoliation (every 42, 63, and 84 days) and fertilization with three levels of nitrogen (N) (0, 100, and 200 kg N ha‐1‐year‐1) and two levels of phosphorus (P) (0 and 75 kg P2O5 ha‐1.year‐1) in a factorial array using a split‐split‐plot experimental design with frequencies in the main plots, N in the sub‐plots, and P in the sub‐subplots with three replications. Soil was a sandy loam Aridisol with a pH of 5.5. Average soil calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), and P contents were 0.6, 0.3, 0.1 and 0.17 meq‐100g‐1 soil, and 6 ppm, respectively. Data from six, four, and three cuttings for the frequencies of 42, 63, and 84 days were analyzed over the total duration of the study (252 days) as well as separately for periods with high (168 days, 384 mm) and low rainfall (84 days, 69 mm). Frequency of defoliation was the only factor that influenced (P≤0.05) the variables studied. In the overall analyses, the highest (P≤0.05) DM yield (3,656 kg#lbha‐1.cutting‐1) was obtained with harvests every 63 days. Mean IVOMD decreased (P≤0.05) from 54.2 to 51.7% with increasing harvest interval from 63 to 84 days, respectively. The average CP content was 7.9%. With low rainfall, mean DM yield was 2,209 kg#lbha‐1, CP content declined (P≤0.05) from 7.5 to 3.9% as the cutting interval increased, and IVOMD decreased (P≤0.05) between 42 and 63 days. With high rainfall, the highest (P≤0.05) DM yield (4,872 kg#lbha‐1) and IVOMD (56.5%) were found at 63 days of age. Mean CP content was 9.3%. These results confirm that A. gayanus is a highly productive forage grass. Lack of response to N and P fertilizers may be attributed partly to relatively low rainfall during the experiment, adaptation of the grass to low fertility soils, and long intervals between N applications and the next harvest.  相似文献   

12.
以2年生烟富3/M26/平邑甜茶幼树为试材,研究了不同施氮水平对苹果矮化中间砧幼树当年及翌年15N 吸收、 利用和分配的影响。结果表明,适量施氮肥利于幼树生长和氮肥利用率的提高,更利于翌年树体生长及氮肥利用率的提高。以不施氮肥（N0）处理为对照,适量施氮肥（N100）或过量施氮肥（N200）条件下均通过促进根系生长进而促进地上部生长,且 N100处理对地上部生长的促进作用较N200更为显著。氮肥施入至春梢旺长期和春梢停长期,N100处理对根系生长的促进作用显著,根冠比由高到低分别为 N100＞N200＞N0,且春梢旺长期根系15N 分配率为 N100(42.93%)＞N200(37.10%)＞N0(26.39%),春梢停长期各处理根系15N分配率由高到低仍为 N100(28.61%)＞N200(20.30%)＞N0(14.27%)。至秋梢旺长期,N100处理生长势显著高于N0,但各器官15N分配率无显著差异;N100与N200处理树体生长势无显著差异,但N100处理地上部15N分配（85.93%）显著高于N200处理(77.28%),根系15N 分配率(14.07%)显著低于N200 处理(22.72%)。至翌年春梢旺长期,N100树体生物量迅速增高至N0 的175.83% 和N200 的176.41%,根冠比和根系15N 分配率显著低于N0和 N200。N200处理始终保持较高的根冠比和根系15N分配率但不利于地上部生长。冬季叶片脱落是苹果矮化中间砧幼树最大的氮流失途径,流失量为当年氮吸收量的44.56%~51.25%。  相似文献   

13.
Rising carbon dioxide (CO2) concentration causes fertilization effects resulting in enhanced crop biomass and yields and thus likely enhances nutrient demand of plants. Hence, this field study was carried out to investigate the effects of elevated CO2 and N on biomass yield, nutrient partitioning, and uptake of major nutrients by soybean (Glycine max L.) using open‐top chambers (OTCs) of 4 m × 4 m size. Soybean was grown in OTCs under two CO2 [ambient and elevated (535 ± 36.9 mg L?1)] and four N levels during July to October 2016. The four N levels were N0, N50, N100, and N150 referring to 0, 50, 100, and 150% recommended dose of N. Both CO2 and N significantly affected biomass and grain yield, though the interaction was non‐significant. CO2 enrichment produced 30–65% higher biomass and 26–59% higher grain yield under various N levels. As compared to the optimum N application (N100), the CO2‐mediated increment in biomass yield decreased with either lower or higher N application, with the response being lowest at N150. As compared to ambient concentration, elevated CO2 resulted in significant reduction of seed P concentration at all N application levels but at N150, an opposite trend was observed. The decrease in seed P was maximum at N0 and N50 (7–9%) and by 3% at N100, whereas there was a gain of 7.5% at N150. The seed N and K concentrations were not affected either by CO2 or N application. Total N, P, and K uptake at harvest were significantly affected by CO2 and N, but not by CO2 × N interaction. Elevated CO2 resulted higher uptake of N by 18–61%, P by 23–62%, and K by 22–62% under various N treatments.  相似文献   

14.
Abstract

Nitrogen (N) fertilizer is a key factor of yield increase but also an environmental pollution hazard. The sustainable agriculture system should have an acceptable level of productivity and profitability and an adequate environmental protection. The objectives of this study were to determine the relationships between N rate, DM yield, plant N concentration (NC) and residual soil nitrate‐nitrogen in order to improve the predicted N rate in corn (Zea mays L.) silage. The experiment was conducted over a period of three years in the province of Quebec on three soil series in a continuous corn crop sequence. Treatments consisted of six rates of N: O, 40, 80, 120, 160, and 200 kg N ha‐1 as ammonium nitrate applied at planting: broadcast and side banded. Four optimum N rates were calculated using different models: (i) economic rate base on fertilizer and corn price using the quadratic model (E); (ii) economic rate based on fertilizer and corn price using the quadratic‐plus‐plateau model (QP); (iii) critical rate based on linear‐plus‐plateau model (P); (iv) lower than maximum rate (L) corresponding to 95% of maximum yield. The optimum plant NC at all growing stages and the N uptake at harvest were calculated depending on these N rates and yields.

The NC of whole plant at 8‐leaf stage (25–30 cm plant height) of ear leaf at tasselling and of whole plant at harvest stage, the N rate, the N uptake at harvest and the DM yield were all significantly intercorrelated and affected by soils and years, but not affected by N fertilizer application method. The DM yield was linearly and significantly related to NC of whole plant at 8‐leaf stage (rv = 0.932**). At this stage, the average NC corresponding to the optimum N rate and yield was of 3.71, 3.68, and 3.66% as calculated with E, L, and P model, respectively. Our data suggest that the NC of whole plant at 8‐leaf stage may be used to evaluate the N nutrition status of plant and the required optimum N fertilizer rate. The NC of ear leaf at tassel stage was also significantly correlated to corn yield (r = 0.994**). It may be used as an indicator to evaluate the near‐optimum N rate in the subsequent years.

The N uptake by whole above‐ground plant at harvest was quadratically related to corn yield. Data show that at high fertilizer N rate, the N uptake still increased without significantly increasing yield. The N uptake was of 176.5, 163.0, and 155.0 kg N ha‐1 using the E, L and P rates of 146, 126, and 115 kg N applied ha‐1, respectively. The optimum N rate and yield were affected by soil type and year, but not by the method of N fertilizer application. The yield increased rapidly up to a N rate of about 120 kg N ha‐1 and then quite slightly to a maximum N rate of 192 kg N ha‐1. The optimum N rate was of 115 and 126 kg N ha‐1 using the P and L model respectively and as high as 146.8 kg N ha‐1 using the E model. The L model, using a much smaller N rate, gave a reasonably high yield compared to E rate (12.2 and 12.5 Mg ha‐1, respectively). The data show that a relatively much lower N rate than maximum did not proportionally diminish the yield. Thus, for a difference of 40.4% between maximum N rate and P rate a difference of only 7.4% in yield was observed. Using the L model the differences in rate and yield were of 34.4% and 4.7%, respectively. The QP model gave no significant difference compared to E model.

At harvest the residual soil NO3‐N increased significantly with increasing N fertilizer rate in whole of the 100 cm soil profile, but mainly in the top 40 cm soil layer. The total NO3‐N found in 0–100 cm profile at rate of 0, 120 and 200 kg applied N ha‐1 at planting was as high as 33.7, 60.5, and 74.5 kg N ha‐1 respectively in a light soil and 37.5, 97.5, and 145.5 kg N ha‐1 in a heavy clay soil. The difference in NO3‐N content in the 60–100 cm layer between different applied N rate suggests that at harvest, part of fertilizer N applied at planting was already leached below the 100 cm soil layer. Results, thus, show that reasonably high corn yields can be obtained using more adequate N fertilizer rates which avoid the overfertilization and are likely to reduce the air and ground water pollution.  相似文献   

15.
Abstract

The experiment was conducted at Kulumsa, South East Ethiopia, using four levels of nitrogen (N) (0, 50,100 and 150?kg N ha?1) and four levels of phosphorus (P) (0, 35, 70 and 105?kg P2O5 ha?1) fertilizers arranged in 4?×?4 factorial arrangements in randomized complete block design with three replications. The available P was increased after harvest due to the application of N and P fertilizer at the rates of 100 or 150?kg N ha?1 and 70 or 105?kg P2O5 ha?1. More specifically, nutrients concentration and nutrient uptake were significantly (p?<?.01) varied among treatment combinations and nutrient use efficiency was declined by increasing N and P after optimum rates. The higher physiological efficiency of N (53.47?kg kg?1) and P (580.41?kg kg?1) and the highest apparent recovery of N (19.62%) and P (2.47%) was recorded from application of 50?kg N ha?1 and P at 70?kg P2O5 ha?1 and the highest agronomic efficiency of N (10.78?kg kg?1) and P (15.25?kg kg?1) was recorded from N at the rate of 50?kg N ha?1 and P at 35?kg P2O5 ha?1, respectively. The combination of N at 100?kg N ha?1 and P at 70?kg P2O5 ha?1 was promising combination that generated highest net benefit 488,878.5 ETB (Ethiopian birr) ha?1 with the highest marginal rate of return (36638%) and gave the highest seed yield (1858.82?kg ha?1) with yield increment of about 57.72% over the control.  相似文献   

16.
Tissue analysis in combination with soil testing has been recently incorporated in the fertilization recommendations for bahiagrass in Florida; however, limited research is available to validate the proposed critical tissue phosphorus (P) level. A greenhouse experiment was conducted to identify the critical minimum tissue P concentration below which bahiagrass dry matter (DM) yield is impacted. Treatments consisted of three nitrogen (N) rates (0, 50, and 100 kg N ha?1), four P rates (0, 20, 40, 60 kg P2O5 ha?1) and two clipping intervals (28 and 56 d). Bahiagrass yields and tissue P increased in response to P application. Phosphorus uptake showed a quadratic response to P rates when N was applied. Phosphorus recovery increased linearly as P rate increased. Root mass responded to P, even at the smallest (20 kg ha?1) rate. Data indicated that tissue P concentration of 1.3 (±0.2) g kg?1 can be used as an indicator of bahiagrass P deficiency.  相似文献   

17.
In this research, radiation use efficiency (RUE) of winter wheat was determined under different irrigation regimes and nitrogen application rates in experimental field at southwest Iran (semi-arid region) in 2009–2010 and 2010–2011. The experiment was laid out as a split plot design, with irrigation treatments as main plots and N fertilization as sub-plots with three replications. Irrigation treatments were 1.2 (I4), 1.0 (I3), 0.8 (I2), and 0.5 (I1) times of the full irrigation requirements and N treatments were 0 (N1), 46 (N2), 92 (N3), and 136 (N4) kg ha?1. Air temperature had significant effects on RUE that was adjusted by multiplication of hourly temperature factor to the hourly values of solar radiation (RUE a ). The values of RUE a were significantly different from the values of RUE in both growing seasons. The values of RUE a ranged from 1.44 to 1.83 g MJ?1 and 1.45 to 1.81 g MJ?1 in 2009–2010 and 2010–2011, respectively. In both growing seasons, minimum and maximum values of RUE were at I1N1 and I4N4 treatments, respectively. The methods of daily maximum and minimum air temperature were modified for considering the effects of air temperature on RUE at locations where hourly air temperature and radiation were not available.  相似文献   

18.
Optimization of phosphorus (P) fertilization is important for balancing soil fertility especially in vertisol to support economic crop production. The objective of the study was to determine the impact of P fertilization (1998 to 2014) on crop yield and nutrient uptake, and soil fertility under continuous annually tilled corn (Zea mays L.)-wheat (Triticum aestivum L.) system in semi-arid Mediterranean conditions. The study was conducted on Arik clay (isohyperthermic, fine clay Typic Haploxerert) using randomized complete block design with four replications for each treatment at the research farm of the Dept. of Soil Science and Plant Nutrition, Çukurova University, Adana, Turkey. P fertilizer at 0, 50, 100, 200 kg P2O5 ha?1 as triple superphosphate (TSP), respectively was applied a week before planting corn. Results showed that increasing P fertilization rates significantly decreased the number of mycorrhizal spores associated with corn roots. Similarly, a 10% decrease in corn root mycorrhizal colonization was observed with 200 kg P2O5 ha?1 fertilization. In the control treatment, corn yield was 4.3 Mg ha?1 as compared to 5.6, 5.7 and 6.1 Mg ha?1 in 50, 100 and 200 kg of P2O5/ha, respectively. The relationship between P fertilization and relative yield showed that more than 95% of the corn yield was produced when P applied at 100 kg P2O5 ha?1. While P fertilization significantly increased the leaf N, P, and K contents but decreased the leaf Zn, Fe and Mn contents, as compared with the control. However, P fertilization did not consistently affect the grain N and P contents. Both physiological efficiency- and agronomic efficiency of P fertilization have shown a significant non-linear increase than that of the control. Total organic C (TOC) and total N (TN) concentrations were more than 34 and 26% higher in 100 and 200 kg P2O5 ha?1rates as compared with the control. Likewise, available P (AP), manganese (Mn) and zinc (Zn) concentrations increased with an increase in P fertilization rates. The AP, Mn and Zn contents significantly stratified by P fertilization. Our results suggested that 100 kg P2O5 ha?1 is optimum to sustain Vertisol fertility for supporting economic corn production in the Mediterranean climates of Turkey.  相似文献   

19.
应用静态明箱-气相色谱法对4 个施氮肥水平N0 [0 kg(N)·hm-2]、N200 [200 kg(N)·hm-2]、N400 [400kg(N)·hm-2]、N600 [600 kg(N)·hm-2]的夏玉米-冬小麦季轮作体系2008~2010 年的土壤温室气体(CH4、CO2 和N2O)排放通量进行研究, 同时观测5 cm 土层土壤温度并记录降水量。结果表明: 太行山前平原冬小麦-夏玉米轮作农田生态系统为CH4 吸收汇, CO2 和N2O 排放源。随着氮肥施入量的增加土壤对CH4 的吸收速率降低, 而CO2 和N2O 的排放速率增加。冬小麦季施氮处理土壤对CH4 的吸收速率显著低于无氮肥的N0 处理, 而N600处理土壤CO2 和N2O 排放速率显著高于N0 处理(P<0.05)。施肥和灌溉会直接导致土壤CO2 和N2O 的排放通量增加, 同时土壤对CH4 的吸收峰值减小。土壤温度升高和降水量增加以及干湿交替加剧均会造成N2O 和CO2排放速率增加。同时在持续干燥和低温条件的冬季不施氮处理观测到土壤对N2O 的吸收现象。N0、N200、N400 和N600 处理土壤CH4 年排放总量(kg·hm-2·a-1)分别为-1.42、-0.75、-0.82、-0.92(2008~2009 年)和-2.60、-1.47、-1.35、-1.76(2009~2010 年), N0、N200、N400 和N600 处理土壤CO2 年排放总量(kg·hm-2·a-1)分别为15 597.6、19 345.6、21 455.9、29 012.5(2008~2009 年)和10 317.7、11 474.0、13 983.5、20 639.3(2009~2010年), N0、N200、N400 和N600 处理土壤N2O 年排放总量(kg·hm-2·a-1)分别为1.05、2.16、5.27、6.98(2008~2009年)和1.49、2.31、4.42、5.81(2009~2010 年)。  相似文献   

20.
探讨秸秆还田与施氮对高纬度黑土区春玉米产量与温室气体排放特性的影响,对促进粮食增产和降低环境代价具有重要意义。本研究通过位于黑土区的大田定位试验,利用静态箱-气相色谱计数方法,在秸秆还田与不还田和3个氮素用量(纯N:120 kg·hm~(-2),240 kg·hm~(-2)和300 kg·hm~(-2))条件下,研究了春玉米不同生育时期农田土壤CO2、N2O和CH4综合温室效应与排放强度,以及土壤过氧化氢酶和脲酶活性的变化。结果表明:无秸秆还田时,高氮用量处理春玉米产量最高;秸秆还田后,中等氮用量处理(240 kg·hm~(-2))春玉米产量最高,且与无秸秆还田的高氮处理间无显著差异。无秸秆还田时,随施氮量增加,CO2、N2O和CH4排放量均显著提高,综合温室效应和土壤温室气体排放量与强度显著增加(P0.05);增施氮肥配合秸秆还田,增加了CO2和N2O的排放量,而土壤CH4的碳汇功能增强,温室气体排放量与强度未显著提高(P0.05)。无秸秆还田,增施氮肥降低了土壤过氧化氢酶活性但提高了土壤脲酶活性;而秸秆还田使得增施氮肥引起的土壤过氧化氢酶活性降低的幅度加大但土壤脲酶活性提高的幅度变小。因此,秸秆还田后配合中等用量氮处理(240 kg·hm~(-2))玉米产量最高,且能够抑制单纯增施氮肥对综合温室效应和土壤温室气体排放强度的促进作用,推荐在生产中参考使用。  相似文献   

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