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1.
Nitrogen (N) fertilizer use in cotton (Gossypium hirsutum L.) production is a potential source of nitrate (NO3 ?) contamination of soils, groundwater, and streams. The McConnell–Mitchell plots, a long-term study of cotton responses to N-fertilization and irrigation methods, were utilized to determine the NO3 ?-N in soil cropped to continuous cotton. The McConnell–Mitchell plots had a split-block experiential design. The main blocks of this test were irrigation methods. Each block of plots was irrigated using a single irrigation method for the entirety of the testing. Nitrogen fertilization rates were tested within each irrigation block. The soil NO3 ?-N content of two irrigation blocks, furrow flow (FI) and center pivot (CP), were compared to the dryland (DL) control block. Nitrogen treatments tested within each irrigation block ranged from 0 to 168.0 kg N ha?1 in 33.6-kg N ha?1 increments. Nitrogen treatments were tested for 18 years (1982 through 1999), discontinued for 4 years (2000 through 2003), and resumed in 2004. Soil samples were taken in the early spring (2000 and 2004) to a depth of 1.50 m in 0.15 m increments and analyzed for NO3 ?-N. Soil samples taken in 2004 were prior to any fertilization treatment. Irrigation method was found to influence the distribution of soil NO3 ?-N. Little accumulation of soil NO3 ?-N was observed in either irrigation block or under dryland production when N rates were less than 67.2 kg N ha?1. Distribution of soil NO3 ?-N in the FI block was significantly different with sample depth and N treatment but not the interaction of depth and treatment in both 2000 and 2004. Presumably, the small and close values of the means and the greater variability of interactions compared to main effects precluded significant interactions. Differences in soil NO3 ?-N in the FI block after suspending N treatments for 4 years were similar to those found in 2000, although the soil NO3 ?-N was generally depleted in 2004 compared to 2000. The distribution of soil NO3 ?-N in the CP-irrigated block was dependent on the interaction of sample depth with N treatment in both 2000 and 2004. Soil NO3 ?-N values and differences tended to be too small to be of discernable or practical importance under CP irrigation. The distribution of soil NO3 ?-N in the DL block was dependent on the interaction of sample depth with N treatment in 2000 and 2004. Soil NO3 ?-N was minimal in the three lowest N treatments (0, 33.6, and 67.2 kg N ha?1) in 2000. Greatest amounts of soil NO3 ?-N were found in conjunction with the 134.4 and 168.0 kg N ha?1 treatments both years. Depletion of soil NO3 ?-N was evident in the surface 0.45 m of the 100.8, 134.4, and 168.0 kg N ha?1 treatments under DL conditions in 2004.  相似文献   

2.
Abstract

A field experiment was conducted at Research Farm of ICAR-Directorate of Groundnut Research, Junagadh for consecutive three summer seasons of 2013, 2014, and 2015 with the objectives of identifying optimum plant density and nutrient doses under check basin irrigation and drip fertigation for higher productivity and net returns. The treatments were; three plant densities viz., 3,33,333 plants/ha (100% of recommended plant density; P1); 4,16,666 plants/ha (125% of recommended plant density; P2), and 4,99,999 plants/ha (150% of recommended plant density;P3) in main plots, and three nutrient doses viz., 18.75–37.5–22.5 NPK kg ha?1 (75% of recommended nutrient dose; F1), 25-50-30 NPK kg ha?1 (100% of recommended nutrient dose; F2), and 31.25–62.5–37.5 NPK kg ha?1 (125% of recommended nutrient dose; F3) in sub-plots, and replicated thrice. The same sets of treatments were tested under both check basin irrigation and drip fertigation. The data were analyzed using split plot design. Pod yield, haulm yield, and net returns were significantly higher with P3 as compared to P1 under check basin irrigation but only haulm yield was found significantly higher with P3 under drip fertigation. Under check basin irrigation, NH4–N, NO3–N, and available P and K in soil were found in the order P1?>?P2?>?P3 (p?<?0.05) while in case of drip fertigation, differences were significant only for available K which was significantly higher in P1 over both P2 and P3. Under check basin irrigation, F2 i.e., application of 100 percent of recommended nutrient doses, being at par with F3, significantly improved pod yield, haulm yield and net returns over that with F1 however, differences were not significant under drip fertigation. NH4–N, NO3–N and available P and K in soil under both the irrigation systems were in the order F3?>?F2?>?F1 (p?<?0.05).  相似文献   

3.
Abstract

Increasing resources use efficiency in intensive cultivation systems of maize (Zea mays L.) can play an important role in increasing the production and sustainability of agricultural systems. The objectives of the present study were to evaluate DM yield and the efficiency of inputs uses under different levels of water, nitrogen (N) and phosphorus (P) in maize. Therefore, three levels of irrigation including 80 (ETc80), 100 (ETc100) and 120% (ETc120) of crop evapotranspiration were considered as the main plots, and the factorial combination of three levels of zero (N0), 200 (N200) and 400 (N400) kg N ha?1 with three levels of zero (P0), 100(P100) and 200 (P200) kg P ha?1 was considered as the sub plots. The results showed that increasing the consumption of water and P was led to the reduction of N and P utilization efficiency, while RUE increased. WUE was also increased in response to application of N and P, but decreased when ETC increased. DM yield under ETc80 treatment reduced by 11 and 12%, respectively, compared to ETc100 and ETc120 which was due to reduction of cumulative absorbed radiation (Rabs(cum)) and RUE. Under these conditions, changes of stomatal conductance (gs) had little effect on DM yield. It was also found that N limitation caused 11 and 20% reduction in DM yield compared to N200 and N400, respectively. This yield reduction was mainly the result of decrease in RUE. By decreasing Rabs(cum), P deficiency also reduced DM yield by 5 and 9%, respectively, relative to P100 and P200 treatments.  相似文献   

4.
Abstract

Soil organic carbon (SOC) sequestration is one of the major agronomic measures to mitigate green house gas emission, enhance food security, and improve agriculture sustainability. The study, therefore, aimed to evaluate crop growth (CG) and radiation use efficiency in spring wheat (Triticum aestivum L.) treated soil with residue type (RT), that is, cowpea (Vigna unguiculata) as legume (LR), maize (Zea mays L.) as cereal (CR) and no residue (NR) treatment applied (5 t ha?1) on dry matter basis. The CR was subsequently incorporated with tillage depths (TD), that is, deep (DT?=?35?cm) and shallow (ST?=?15?cm) as main plot treatments. The N was applied in two splits starting from 0 to 160?kg ha?1 as sub plot treatments. Experiment was conducted in two CG seasons 2009–11 at Agronomy Research Farm, the University of Agriculture Peshawar, Pakistan. Results showed the highest CG and RUE with LR incorporated than CR and/or NR with DT. Increasing N-rate resulted an increase in CG, RUE and biomass of wheat. Residue of LR or CR deeply incorporate into the soil has resulted healthy traits (i.e., tillers- and spikes number), which resulted higher biomass. Nitrogen applied 120?kg ha?1 resulted in higher CG, RUE and grain yield for treatment LR, followed by CR and the lowest for the NR. Crop of second year showed higher grain yield, which was due to healthy traits including better CG and RUE. The study suggests that CR of LR or CR nature incorporated deep into the soil can optimize crop N-fertilizer demand for optimum production, which protects environment from the excessive use of N application.  相似文献   

5.
Methane (CH4) emission from flooded rice fields was measured hourly over 24 h for rice (Oryza sativa L.) seasons in 2008 and 2009. The objectives of this study were to identify typical diel variation in CH4 emission and to estimate the best time of day for optimum extrapolation of daily CH4 emission. Our results showed distinct diel variation in CH4 emission, which exhibited a maximum at 14:00–15:00 and a minimum at midnight. About 5.2–5.6% of total CH4 emitted per day (110–160 mg CH4 m?2 d?1) was released at 14:00–15:00. The diel pattern of CH4 emission resembled that of air temperature (Ta). The Ta coupled with solar radiation could cause a difference in partial pressure of CH4 (DPPC) through the gas conduit of the plant. The best extrapolation of daily CH4 emission was achieved with data observed at 10:00–11:00. We concluded that DPPC-induced CH4 emission is an important mechanism causing diel variation.  相似文献   

6.
The intensive winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) cropping systems in the North China Plain (NCP) rely on the heavy use of mineral nitrogen (N) fertilizers. As the fertigated area of wheat and maize in the NCP has grown rapidly during recent years, developing N management strategies is required for sustainable wheat and maize production. Field experiments were conducted in Hebei Province during three consecutive growth seasons in 2012–2015 to assess the influence of different N fertigation rates on N uptake, yield, and nitrogen use efficiency [NUE: recovery efficiency (REN) and agronomic efficiency (AEN)]. Five levels of N application, 0 (FN0), 40 (FN40%), 70 (FN70%), 100 (FN100%), and 130% (FN130%) of the farmer practice rate (FP: 250 kg N ha?1 and 205.5 kg N ha?1 for wheat and maize, respectively), corresponding to 0, 182.2, 318.9, 455.5, and 592.2 kg N ha?1 y?1, respectively, were tested. Nitrogen in the form of urea was dissolved in irrigation water and split into six and four applications for wheat and maize, respectively. In addition, the treatment “drip irrigation + 100% N conventional broadcasting” (DN100%) was also conducted. All treatments were arranged in a randomized complete block design with three replications. The results revealed the significant influence of both N fertigation rate and N application method on grain yield and NUE. Compared to DN100%, FN100% significantly increased the 3‐year averaged N recovery efficiency (REN) by 0.09 kg kg?1 and 0.04 kg kg?1, and the 3‐year averaged N agronomic efficiency (AEN) by 2.43 kg kg?1 and 1.62 kg kg?1 for wheat and maize, respectively. Among N fertigation rates, there was no significant increase in grain yield in response to N applied at a greater rate than 70% of FP due to excess N accumulation in vegetative tissues. Compared to FN70%, FN100%, and FN130%, FN40% increased the REN by 0.17–0.57 kg kg?1 and 0.03–0.34 kg kg?1and the AEN by 4.60–27.56 kg kg?1 and 2.40–10.62 kg kg?1 for wheat and maize, respectively. Based on a linear‐response relationship between the N fertigation rate and grain yield over three rotational periods it can be concluded that recommended N rates under drip fertigation with optimum split applications can be reduced to 46% (114.6 kg N ha?1) and 58% (116.6 kg N ha?1) of FP for wheat and maize, respectively, without negatively affecting grain yield, thereby increasing NUE.  相似文献   

7.
Halophytes could withstand the hyper-salinity soil and survive widely in areas where soil salt content is high because they can endure salt stress to a certain extent. Lycium ruthenicum Murr (LRM), with significant nutritional and medicinal values, is one of the most important native halophytes in the arid oasis-desert transition zone of northwestern China. In recent years, artificially planting LRM has been being popular since it can improve saline-alkalized soil and increase the income of local farmers as well. More efforts about the artificial planting of LRM are put in enhancing the productivity and quality, but survivorship of LRM seedling by appropriate saline irrigation is still unclear in arid areas. A field experiment was conducted to explore the responses of LRM to four levels of saline water irrigation (Ec of irrigation water: 2.00?μs?cm?1 (T1), 4.51?μs?cm?1 (T2), 6.89?μs?cm?1 (T3), and 9.00?μs?cm?1 (T4)) during the growing seasons in 2014 and 2015. The average soil electrical conductivity (Eca) in 0–60 cm depth increased while the biomass of LRM decreased with increasing Ec of irrigation water, and the differences of Eca among treatments decreased with increasing salinity level. In contrast to previous research findings, salt stress had more significant effect on photosynthesis and chlorophyll fluorescence of LRM, in which great changes were caused by a threshold following the increased salinity. Most of the light energy absorbed by LRM was used for photosynthesis and heat dissipation when soil salinity was low, what was used for chlorophyll fluorescence when soil salinity was high. The results of the experiment indicate that T2 was the most suitable irrigation method for artificially planting LRM in the field, and it’s the key to save freshwater resources in arid areas and improve the production of saline-alkali land.  相似文献   

8.
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   

9.
Leaching with deep drainage is one of the loss pathways of carbon (C) and nitrogen (N) in cropping fields. However, field studies in irrigated row cropping systems are sparse. A 3‐year investigation on C and N leaching associated with deep drainage was overlaid on a long‐term experiment on tillage practices and crop rotations in Australia. The treatments included cotton (Gossypium hirsutum L.) monoculture and cotton–wheat (Triticum aestivum L.) or maize (Zea maize L.) rotations with maximum or minimum tillage. The deep drainage C and N concentrations at 0.6 and 1.2 m depth were measured after furrow irrigation with ceramic cup samplers during the 2014–15, 2015–16 and 2016–17 cotton seasons. Pre‐planting dissolved organic carbon (DOC) concentration in soil at 0.6–1.2 m depth during 2016–17 was 64 mg kg?1 for maximum tilled cotton monoculture, 36 mg kg?1 for minimum tilled cotton monoculture and 39 mg kg?1 for cotton–wheat, and in maize and cotton subplots 51 and 41 mg kg?1, respectively. Post‐harvest DOC values in soil were similar in all treatments (average of 32 mg DOC kg?1). Total organic carbon (TOC) losses in deep drainage were equal to 2%–30% of TOC gained in irrigation water. Oxidized N losses in deep drainage ranged from 0.7% to 12% of applied N (260 kg ha?1). NOx‐N concentrations in leachate under maize systems (20 mg L?1) were up to 73% lower than those in cotton systems (75 mg L?1). Maize sown in rotation with cotton can improve cotton yield, reduce N leaching and improve N use efficiency of subsequent cotton.  相似文献   

10.
In order to optimize N application and understand how the different combinations of water and N management affect grain filling characteristics and yield, we designed three irrigation regimes (W1 submerged irrigation, W2 alternate irrigation, W3 dry cultivation), and different N application strategies at 180 kg ha?1 in 2010 and 2011. The relationship between grain filling characteristics and grain yield formation were respectively investigated. The results revealed that there were obvious interacting effects of irrigation regime and N application strategies on grain yield and grain-filling characteristics as well. Compared with W1 and W3 treatments, under W2, the N-fertilizer should account for 30% base, 30% tillering, and 40% panicle fertilizer with the last being applied equally at 4th and 2nd leaves emerged from the top. Correlation analysis revealed that grain filling rate during middle grain-filling stage was the largest and contribute more than 50% to grain-filling. Grain yield was significantly related to grain filling rate (Gmax or Gmean), final weight of a kernel (A), and mean grain filling rate (MGR) of the early, mid and late stages during grain filling in inferior spikelets, which is the important reason for water and N coupling effect further to increase yield and fertilizer use efficiency.  相似文献   

11.
Acetylene blockage was evaluated as a method for measuring losses of N2O + N2 from two Denchworth series clay soils. The denitrification potential in anaerobic, dark incubations at 20°C with nitrate (equivalent to 100 kg N ha?1 0–20 cm depth), maximum water holding capacity, and acetylene (1%), was equivalent to 32 ± 11 and 39 ± 6 kg N ha?1 per day for the two 0–20 cm soils and was positively correlated with carbon content (r= 0.98). After 4 days N2O was reduced to N2 in the presence of C2H2. In April 1980 following irrigation (24 mm) and applications of ammonium nitrate (70 kg N ha?1) and acetylene, the mean nitrous oxide flux from soil under permanent grass was 0.05 ± 0.01 kg N2O-N ha?1 per day for 8 days. In June 1980, the losses of nitrogen from cultivated soils under winter wheat after irrigation (36 mm) and acetylene treatment were 0.006 ± 0.002 and 0.04–0.07 ± 0.01 kg N ha?1 per day respectively before and after fertilizer application (70 kg N ha?1). The nitrous oxide flux in the presence of acetylene decreased briefly, indicating that nitrification was rate determining in drying soil.  相似文献   

12.
Flood irrigated date-palm orchards annually manured for 10 (=U10), 50 (=U50, 110 (=U110) and 230 (U230) years together with a barren site in a nearby desert (=U0) all on sandy soils, were analysed for total P (TP), organic P (OP), inorganic P extracted by 0.5 m H2SO4 (Ca-P), inorganic P not extracted by 0.5 m H2SO4 (NP), total N (TN) and organic C (TC). Watering resulted in continuing CaCO3 accumulation in the soils. TC and TN to 160 cm depth increased rapidly over the first 50 years (120 g C m?2 a?1 and 9.7 g N m?2 a?1), then the increases slowed. In contrast, TP continued to accumulate steadily (4.8 g P m?2 a?1). AtU0, TP to 160 cm depth was very small (= 88 mg kg?1) and dominated by Ca-P with OP as a minor component. At U10, OP and Ca-P were in equal proportions. The latter acquired increasing dominance with increasing period of treatment whereas OP reached a steady state. NP increased at a rate which decreased with time. It is likely that most of OP compounds have been leached down the profile where mineralization and subsequent immobilization, probably by Ca2+ ions from irrigation waters, have occurred.  相似文献   

13.
The scarcity of non-renewable fertilizers resources and the consequences of climate change can dramatically influence the food security of future generation. Introduction of high yielding varieties, intensive cropping sequence and increasing demand of food grains day-by-day, application of recommended dose of fertilizers could not fulfill our targets due to outdated fertilizers recommendations are yet in practice. It not only alters soil quality, nutrient balance, microbial and enzymatic ecology but also affected productivity and sustainability of rice in Gangetic alluvial soils of India. The effect of fertilizers application based on “fertilizing the soil versus fertilizing the crop” which insure real balance between the applied and available soil nutrient is urgently needed. Hence, the present study was conducted during three consecutive crop seasons (2010, 2011, and 2012) to assess the effect of imbalance and balance fertilization based on initial soil test values and targeted yields, and to determine the effect of farmyard manure (FYM) when superimposed with balanced fertilizers on identification of minimum data set for the development soil quality, nutrient acquisition, and grain yield of rice. The six fertilizer treatments were laid out in a randomized block design with three replications. The treatments were: T1-control (no fertilization), T2-farmyard manure @ 5 t ha?1, T3-farmers practice (60:30:30 kg N:P2O5:K2O ha?1), T4-precise application of mineral fertilizers based on initial soil test values (77:24:46 kg N:P2O5:K2O ha?1) for targeted grain yield of 4.0 t ha?1, T5-precise application of mineral fertilizers based on initial soil test values (74:23:43 kg N:P2O5:K2O ha?1) plus FYM (5 t ha?1) for targeted grain yield of 4.0 t ha?1 and T6-precise application of mineral fertilizers based on initial soil test values (135:34:65 kg N:P2O5:K2O ha?1) for targeted rice grain yield of 5.0 t ha?1. Result revealed that the targeted rice grain yield of 4.0 and 5.0 t ha?1 was achieved in T4 and T6 treatments with 1.59% (4.06 t ha?1) and –3.40% (4.83 t ha?1) deviations, respectively. T4, T5, and T6 significantly increased crop growth, nutrient uptake, available P (Pa) and K (Ka) and augmented rice grain yield by 10.6, 20.2 and 31.6%, respectively, over T3. Microbial biomass carbon, soil respiration and enzymatic activity were enhanced significantly in T5 as compared to T6. Highest soil quality index was found in T5 (0.95) followed by T6 (0.90) and, lowest was in T1 (0.63). The contribution of minimum data set (MDS) toward the SQI was in the descending order of ALP (30.6%) > SOC (21.5%) > Ka (11.3%) > PSM (9.68%) > Na (8.51%). Overall, rice yield and soil quality was improved by using balance fertilization based on fertilizing the crop Vs fertilizing the soil in alluvial soils of India.  相似文献   

14.
Research was performed during the 2010 and 2011 growing seasons to investigate the effect of zeolite and zinc (Zn) foliar application on the qualitative characteristics and oil yield of canola cultivars at different moisture regimes. A factorial split-plot experiment was performed on the basis of the randomized complete block design with three replications in the Seed and Plant Improvement Institute, Karaj, Iran. The treatments were as follows: (1) irrigation (I), complete (I1), and restricted (I2) at the pod formation stage, (2) zeolite (Z), 0 (Z1), and 15 t ha?1 (Z2), and (3) Zn, zinc sulfate concentrations of 0%, 0.1%, and 0.2 % (Zn1, Zn2, and Zn3) at the pod formation stage. These treatments were applied on Licord, RGS003, and Opera cultivars. The results show that the simple effect of treatments were statistically significant for all assessed traits at P < 0; as well as the interaction effects of Z and Zn (P < 0.01) and the interaction effects of I and cultivar (P < 0.01). The greatest rates of all studied traits were obtained by applying Z2Zn2 (15 ton ha?1 zeolite and 0.1% Zn sulfate) in both irrigation regimes. The rates of grain yield, biological yield, and harvest index improved by 43.82%, 73.99%, and 30.04%, respectively, using a combined application of Z and Zn. Therefore, based on the low cost of natural Z and a low Zn intake, these treatments could be used to enhance the performance of canola, especially in regions that are exposed to water stress.  相似文献   

15.
华北山前平原农田土壤硝态氮淋失与调控研究   总被引：11，自引：5，他引：6  
本文依托中国科学院栾城农业生态系统试验站小麦-玉米一年两熟长期定位试验, 应用土钻取土和土壤溶液取样器取水的方法, 研究了不同农田管理措施下土壤硝态氮的累积变化, 计算了不同氮肥处理通过根系吸收层的硝态氮淋失通量。结果表明, 小麦-玉米生长季土壤硝态氮累积量和淋失量随着施氮量的增加显著增加, 相同氮肥水平下增施磷、钾肥增加了作物的收获氮量, 施磷肥增加的作物收获氮量最高可达123kg·hm-2·a-1, 施钾肥增加的作物收获氮量最高为31 kg·hm-2·a-1。不同灌溉水平下0~400 cm 土体累积硝态氮随着灌溉量的增加而降低, 控制灌溉(小麦季不灌水, 玉米季灌溉1 水)、非充分灌溉(小麦季灌溉2~3 水, 玉米季按需灌溉)、充分灌溉(小麦季灌溉4~5 水, 玉米季按需灌溉)各处理剖面累积硝态氮量分别为1 698 kg·hm-2、1148 kg·hm-2 和961 kg·hm-2。与非充分灌溉和充分灌溉处理相比, 控制灌溉在100~200 cm 土层硝态氮累积量显著高于其他层次, 2003~2005 年间控制灌溉剖面增加的硝态氮量占施肥总量的23%; 非充分灌溉处理剖面增加的硝态氮量占施肥总量的22%; 充分灌溉处理剖面增加的硝态氮量占施肥总量的47%。免耕措施降低了作物产量, 影响土壤水的运移, 增加了硝态氮的淋失风险。根据作物所需降低氮素投入(N 200 kg·hm-2·a-1), 增施磷、钾肥, 控制灌溉量是减少华北山前平原地区硝态氮淋失, 保护地下水的有效措施。  相似文献   

16.
Abstract

Field experiment was conducted for 7 years continuously to evaluate the influence of combined application of organic and inorganic fertilizer on soil fertility buildup and nutrient uptake in mint (Mentha arvensis) and mustard (Brassica juncea) cropping sequence. Maximum organic carbon was observed under full supply of organic manure (T2; FYM at 20 t ha?1) averaged across all the Stages of cropping sequence. It was increased by 38, 50, and 51% in T2 in Stages I (after mint harvest/presowing of dhaincha), II (after incorporation of dhaincha (Sesbania aculeata)/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective controls. In general, magnitude of organic carbon was recorded higher in Stage II after green manuring of Sesbania compared with Stages I and III. Nitrogen availability in treated plots was increased by 26.0–89.9, 15.2–64.5, and 4.9–52.0% in Stages I (after mint harvest/presowing of Sesbania), II (after incorporation of dhaincha/presowing of mustard), and III (after harvest of mustard/preplanting of mint), respectively, over their respective control. Average across all the three Stages showed a positive balance of nitrogen (N), phosphorus (P), and potassium (K) in soil under different treatments. Mean of the three Stages indicated that maximum available N, P, and K were increased by 36.1, 129.0, and 65.20% in T4 (N:P:K: 133:40:40 and FYM at 6.7 t ha?1), T4 (N:P:K::133:40:40 and FYM at 6.7 t ha?1), and T3 (N:P:K::100:30:30 and FYM at 10 t ha?1), respectively, over their initial status. Supply of organic and inorganic fertilizer (T4; N:P:K::133:40:40 and FYM at 6.7 t ha?1) was found most suitable combination with respect to N, P availability in soil, and productivity of mint and mustard crop.  相似文献   

17.
The relationship between the two radiant fluxes is studied from almost a 3-year data archive of hourly photosynthetically active photon flux (QP) and global solar irradiance (RS) performed at Athalassa, Cyprus. These data are used to determine temporal variability of the ratio (QP/RS) and its dependence on sky conditions. The seasonal variation of the ratio obtained from daily data ranges from 1.942 E MJ−1 (summer) to 1.892 E MJ−1 (winter) with an annual mean value of 1.919 E MJ−1. The ratio increased from 1.865 to 2.01 E MJ−1 (daily values) or from 1.878 to 2.197 μE J−1 (hourly values), as sky conditions changed from clear to overcast. Effective atmospheric parameters such as sky clearness, brightness and path length were found to cause substantial changes to the PAR fraction.  相似文献   

18.
The objectives of this 2-year field study were to assess the effects of irrigation and nitrogen (N) application on nitrous oxide (N2O). Soil N2O flux was determined using open-bottomed chambers. Nitrous oxide concentrations were determined with gas chromatography. The results showed that in 2008, N2O emission rates ranged from 2.0 to 50.0 g N ha?1 d?1 in the alternating furrow irrigation and N application treatments (AFINA) and from 2.4 to 68.4 g N ha?1 d?1 in the conventional every-furrow irrigation and fertilization treatment (CIF). In 2009, cumulative N2O-N loss in the optimal combination with greater yields and lower N2O emission in AFINA was 1277 g N ha?1 compared to 1695 g N ha?1 with CIF. The study indicated that AFINA practices combined with optimum N fertilizer and irrigation rates could reduce soil N2O emission and water input compared to CIF practices without causing a decline in corn yield.  相似文献   

19.
A field experiment was conducted over two years to evaluate the gas exchange, water relations, and water use efficiency (WUE) of wheat under different water stress and nitrogen management practices at Crop Physiology Research Area, University of Agriculture, Faisalabad, Pakistan. Four irrigation regimes and four nitrogen levels, i.e., 0, 50, 100, and 150 kg N ha?1 were applied in this study. The photosynthetic gas exchange parameters [net carbon dioxide (CO2) assimilation rate, transpiration rate and stomatal conductance] are remarkably improved by water application and nitrogen (N) nutrition. Plants grown under four irrigation treatments as compared with those grown under one irrigation treatment average stomatal conductance increased from 0.15 to 0.46 μ mol m?2s?1mol during 2002–2003 and 0.18 to 0.33 μ mol m?2s?1mol during the year 2003–2004 and photosynthetic rate from 9.33 to 13.03 μmol CO2 m?2 s?1 and 3.99 to 7.75 μmol CO2 m?2 s?1 during the year 2002–2003 and 2003–2004, respectively. The exposure of plants to water and nitrogen stress lead to noticeable decrease in leaf water potential, osmotic potential and relative water content. Relative water content (RWC) of stressed plants dropped from 98 to 75% with the decrease in number of irrigation and nitrogen nutrition. The higher leaf water potential, and relative water contents were associated with higher photosynthetic rate. Water use efficiency (WUE) reduced with increasing number of irrigations and increased with increasing applied nitrogen at all irrigation levels.  相似文献   

20.
ABSTRACT

This study mainly focused on the impacts of vermicompost (VC) treatments on physicochemical characteristics of sandy-clay-loam soil and lettuce (Lactuca sativa var. crispa) yield in a greenhouse under different soil moisture regimes. Pot experiments were conducted with different VC treatment doses (0%, 2.5%, and 5% w/w) and three soil water regimes (100%, 50%, and 25%?f, ?f is field capacity). Following the harvest, soil samples were taken and analyzed for physicochemical properties. The highest organic matter content (2.19%) was observed in 5% VC treatment of the full irrigation level (100%?f) irrigation treatment and the lowest organic matter content (0.19%) was obtained from the control treatment of the lowest irrigation level (25%?f). Soil physical properties were positively influenced by VC treatments under different irrigation regimes. The highest lettuce yield (178.7 g plant?1) was observed in 5% VC treatment of the full irrigation level (100%?f) irrigation treatment and the lowest lettuce yield (94.0 g plant?1) was obtained from the control treatment of the lowest irrigation level (25%?f). Present findings revealed that vermicompost treatments under different irrigation regimes could reliably be used to enhance soil physicochemical properties and lettuce yield.  相似文献   

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