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1.
The presence of arsenic in irrigation water and in paddy field soil were investigated to assess the accumulation of arsenic
and its distribution in the various parts (root, straw, husk, and grain) of rice plant from an arsenic effected area of West
Bengal. Results showed that the level of arsenic in irrigation water (0.05–0.70 mg l−1) was much above the WHO recommended arsenic limit of 0.01 mg l−1 for drinking water. The paddy soil gets contaminated from the irrigation water and thus enhancing the bioaccumulation of
arsenic in rice plants. The total soil arsenic concentrations ranged from 1.34 to 14.09 mg kg−1. Soil organic carbon showed positive correlation with arsenic accumulation in rice plant, while soil pH showed strong negative
correlation. Higher accumulation of arsenic was noticed in the root (6.92 ± 0.241–28.63 ± 0.225 mg kg−1) as compared to the straw (1.18 ± 0.002–2.13 ± 0.009 mg kg−1), husk (0.40 ± 0.004–1.05 ± 0.006 mg kg−1), and grain (0.16 ± 0.001–0.58 ± 0.003 mg kg−1) parts of the rice plant. However, the accumulation of arsenic in the rice grain of all the studied samples was found to
be between 0.16 ± 0.001 and 0.58 ± 0.003 mg kg−1 dry weights of arsenic, which did not exceed the permissible limit in rice (1.0 mg kg−1 according to WHO recommendation). Two rice plant varieties, one high yielding (Red Minikit) and another local (Megi) had been chosen for the study of arsenic translocation. Higher translocation of arsenic was seen in the high yielding variety
(0.194–0.393) compared to that by the local rice variety (0.099–0.161). An appreciable high efficiency in translocation of
arsenic from shoot to grain (0.099–0.393) was observed in both the rice varieties compared to the translocation from root
to shoot (0.040–0.108). 相似文献
2.
Insufficient puddling with inappropriate implements or imprecise time/intensity may alter saturated water flow in paddy soil
spatially or temporary due to change in aggregate size distribution, dry bulk density, saturated hydraulic conductivity, and
percolation rate of the soil. In this study, spatial variability of saturated hydraulic conductivity (K
s), a key parameter of the saturated water flow, in Fuchu Honmachi paddy plot (100 m × 28 m) was characterized based on dielectric
or ADR dry bulk density (ρb-ADR) with help of non-similar media concept (NSMC) and geostatistics model to meet its correlation to subsurface percolation.
A 100 cc core and an ADR data were sampled from each sub-plot (7 m × 7.5 m), and then were used for measuring and predicting
ρb and K
s. The predicted data agreed with the measured ones, in which they fitted well the x = y line with RMSE of 0.029 cm3 cm−3 (R
2 = 0.68), 0.027 g cm−3 (R
2 = 0.71) (ρb), and 0.098 cm d−1 (R
2 = 0.45) for θ, ρb, and K
s, respectively. The predicted ρb and K
s had similar trend in spatial variability to the measured ones particularly within the distance of 46.3–51.9 m and 26.2–27.9 m,
respectively. The spatial variability of the predicted K
s coincided to that of the subsurface percolation rate, in which they had similar distance of dependence. The results indicated
that the presenting method can be reasonably accepted. 相似文献
3.
S. F. Mousavi F. Kamyab-Talesh M. R. Yazdani S. H. Saghaian-Nejad 《Paddy and Water Environment》2011,9(4):385-392
Percolation loss of water in rice fields is a major cause of low water use efficiency. Variation of infiltration rate and
soil compactness in four paddy fields (with clay, silty clay, clay loam, and loam textures) was investigated in northern Iran.
In each field, in longitudinal and transverse directions, points located 0.5, 2.5, 6.5, 12.5, … m from the bunds were selected
and water infiltration rate and resistance to penetration of a pocket penetrometer were measured. The results showed that
in clay soil, average final infiltration rate (f
c) in longitudinal direction, transverse direction, and center of the field was 0.216, 0.136, and 0.08 cm day−1, respectively. The f
c for loamy soil was 2.77, 2.32, and 0.409 cm day−1, respectively. Similar differences were observed in the other two soil textures. In general, effect of direction of the field
for measuring infiltration rate was not statistically significant. Loam and clay loam soils, with resistance to penetration
of 0.37 and 0.33 kg cm−2, were not significantly different. But, clay and silty clay soils with resistance to penetration of 0.25 and 0.14 kg cm−2 were significantly different (P < 0.05). Resistance to penetration of the penetrometer was not affected significantly (P < 0.05) by direction of measuring this parameter in the field. The conclusion is that if measured soil physical properties
in a paddy field are going to be representative of the whole field, they should be measured at different locations, especially
near the bunds. Another strategy for obtaining a representative infiltration rate or compactness for a paddy field is uniform
puddling of the field. 相似文献
4.
Two water management practices, an intermittent irrigation scheme using automatic irrigation system (AI) and a spillover-irrigation
scheme (SI), were compared for the fate and transport of commonly used herbicides, mefenacet (MF) and bensulfuron-methyl (BSM)
in experimental paddy plots. Maximum mefenacet concentrations in paddy water were 660 and 540 μg L−1 for AI and SI plot, respectively. The corresponding values for bensulfuron-methyl were 46.0 and 42.0 μg L−1. Dissipation of the herbicides in paddy water appeared to follow the first-order kinetics with half-lives (DT50) of 1.9–4.5 days and DT90 (90% mass dissipation) of 7.8–11.3 days. The AI plot had no surface drainage, hence no herbicide was lost through paddy-water
discharge. However, SI plot lost about 38 and 49% of applied mefenacet and bensulfuron-methyl, respectively. The intermittent
irrigation scheme using automatic irrigation system with a high drainage gate was recommended to be a best management practice
for controlling the herbicide losses from paddy fields. The paddy field managed by spillover-irrigation scheme may cause significant
water and herbicide losses depending on the volume of irrigation and precipitation. The water holding period after herbicide
application was suggested to be at least 10 days according to the DT90 index. 相似文献
5.
Mukund D. Patil Bhabani S. Das Eran Barak Pratap B. S. Bhadoria Amir Polak 《Paddy and Water Environment》2010,8(2):189-198
Polymer-coated urea (PCU) is an important alternative to uncoated urea for improving nitrogen (N) use efficiency (NUE). Only
a few studies discuss their utility for lowland rice systems. A 2-year field study was conducted to examine if nitrogen loading
is reduced in lowland rice ecosystem by using mixture of PCU and uncoated urea without sacrificing yield. Five treatments
involving two mixtures of PCU with 50 and 70% coated urea each at 70 and 50% of recommended dose (80 kg N ha−1) and one with uncoated urea at 100% recommended dose were laid out in a completely randomized design. Selected plant growth
parameters and plant available N contents (NH4–N plus NO3–N) in soil solution and ponded water were measured over a period of 65 days after transplanting. Results showed no significant
difference for vegetative and yield parameters among different treatments suggesting that treatments receiving lower doses
of nitrogen exhibited higher NUE. Analysis of partial factor of productivity (PFP) for N suggested that the total N dose may
be reduced by 50% using mixtures of coated and uncoated urea. Similarly, statistically similar PFP values for treatments receiving
the same amount of total N for both years and for both total N dose suggested that the proportion of coated urea may also
be reduced to as low as 50% without sacrificing yield. Correlation analysis on nitrogen contents in ponded water and soil
solutions and the analysis of water productivity and PFP showed that soil water regime could also significantly influence
the nitrogen status in soil even when PCU are applied. In turn, both the water regime and N contents in soil ultimately influences
grain yield. Although the constant release of N from coated fertilizer ensures adequate N supply for plant uptake, it may
not completely avoid N deficit condition especially during heavy rainfall. Analysis of the developed production function suggested
that 55–65% polymer coating and about 100 cm total water input may be ideal for achieving maximum yield. The production function
was developed for PCU treatments using data observed in treatments receiving 70% recommended N dose. The range of water input
in these treatments was 86.5–174.0 cm. 相似文献
6.
A field experimental study was performed during the growing season of 2001 to evaluate water and nutrient balances in paddy
rice culture. Three plots of standard fertilization (SF), excessive fertilization (EF, 150% of SF), and reduced fertilization
(RF, 70% of SF) were used and the size of treatment plot was 3,000 m2, respectively. The hydrologic and water quality was field monitored throughout the crop stages. The water balance analyses
indicated that approximately half (47–54%) of the total outflow was lost through surface drainage, with the remainder consumed
by evapotranspiration. Statistical analysis showed that there was no significant effect of fertilization rates on nutrient
outflow through the surface drainage or rice yield. Reducing fertilization of rice paddy may not work well to mitigate the
non-point source nutrient loading in the range of normal farming practices. Instead, the reduction in surface drainage could
be important to controlling the loading. Suggestive measures that may be applicable to reduce surface drainage and nutrient
losses include water-saving irrigation by reducing ponded water depth, raising the weir height in diked rice fields, and minimizing
forced surface drainage as recommended by other researchers. The suggested practices can cause some deviations from conventional
farming practices, and further investigations are recommended. 相似文献
7.
Nitrogen and phosphorus leaching losses from paddy fields with different water and nitrogen managements 总被引:6,自引:2,他引:4
Shi-Zhang Peng Shi-Hong Yang Jun-Zeng Xu Yu-Feng Luo Hui-Jing Hou 《Paddy and Water Environment》2011,9(3):333-342
While many water-saving rice production techniques have been adopted in China, the environmental effects of these techniques
require further investigation. This study aims to assess nitrogen (N) and phosphorus (P) leaching losses under real conditions
in different water and N managements. Two water and three N treatments are conducted in the Taihu Lake region of China. Results
show that the total N leaching losses during the rice season under flooding irrigation (FI) are 12.4, 9.31, and 7.17 kg ha−1 for farmers’ fertilization practices (FFP), site-specific N management (SSNM), and controlled-release nitrogen fertilizer
management (CRN), respectively. Under controlled irrigation (CI), the respective losses were 7.40, 5.86, and 3.79 kg ha−1 for the same management methods. The total P leaching losses during the rice season under FI were 0.939, 0.927, and 0.353 kg ha−1 for FFP, SSNM, and CRN, respectively. Under CI, the losses were 0.424, 0.433, and 0.279 kg ha−1, respectively, for the same management methods. Ammonium and nitrate N accounted for 42.2–65.5% and 11.8–14.7% of the total
nitrogen leaching losses under different water and N management methods, respectively. Due to significant decrease of volumes
of percolation water and nitrogen and phosphorus concentrations in percolation water, N and P leaching losses were reduced
in the CI treatment compared to the FI treatment under the same N management. The reduction of N input and application of
controlled-release nitrogen fertilizer can reduce N and P leaching losses from paddy fields. 相似文献
8.
Jae Young Cho Jae Gwon Son Jin Kyu Choi Chang Hoon Song Byung Yeoup Chung 《Paddy and Water Environment》2008,6(2):211-219
The present study was carried out to evaluate nutrient losses that occur during the course of agricultural activity from rice
paddy fields of reclaimed tidal flat. For this study, we chose a salt-affected rice paddy field located in the Saemangeum
reclaimed tidal area, which is located on the western South Korean coasts. The plot size was 1,000 m2 (40 m × 25 m) with three replicates. The soil belonged to the Gwanghwal series, i.e., it was of the coarse silty, mixed,
mesic type of Typic Haplaquents (saline alluvial soil). The input quantities of nitrogen and phosphorus (as chemical fertilizer)
into the experimental rice paddy field were 200 kg N ha−1 and 51 kg P2O5 ha−1 per annum, and the respective input quantities of each due to precipitation were 9.3–12.9 kg N ha−1 and 0.4–0.7 kg P ha−1 per annum. In terms of irrigation water, these input quantities were 4.5–8.2 kg N ha−1 and 0.3–0.9 kg P ha−1 per annum, respectively. Losses of these nutrients due to surface runoff were 22.5–38.1 kg N ha−1 and 0.7–2.2 kg P ha−1 for the year 2003, and 26.8–29.6 kg N ha−1 and 1.6–1.9 kg P ha−1 for the year 2004, respectively. Losses of these nutrients due to subsurface infiltration during the irrigation period were
0.44–0.67 kg N ha−1 and 0.03–0.04 kg P ha−1 for the year 2003, and 0.15–0.16 kg N ha−1 and 0.05–0.06 kg P ha−1 for 2004. When losses of nitrogen and phosphorus were compared to the amount of nutrients supplied by chemical fertilizers,
it was found that 11.3–19.1% of nitrogen and 0.5–1.7% of phosphorus were lost via surface runoff, whereas subsurface losses
accounted to 0.2–0.8% for nitrogen and only 0.02–0.04% for phosphorus during the 2-year study period. 相似文献
9.
V. Phogat A. K. Yadav R. S. Malik Sanjay Kumar Jim Cox 《Paddy and Water Environment》2010,8(4):333-346
The HYDRUS-ID model was experimentally tested for water balance and salt build up in soil under rice crop irrigated with different
salinity water (ECiw) of 0.4, 2, 4, 6, 8 and 10 dS m−1 in micro-lysimeters filled with sandy loam soil. Differences of means between measured (M) and HYDRUS-1D predicted (P) values of bottom flux (Q
o) and leachate EC as tested by paired t test were not found significant at P = 0.05 and a close agreement between RMSE values showed the applicability of the HYDRUS-1D to simulate percolation and salt
concentration in the micro-lysimeters under rice crop. Potential ET values of rice as obtained from CROPWAT matched well with
model predicted and measured one at all ECiw treatments. The model predicted root water uptake varied from 66.1 to 652.7 mm
and the maximum daily salt concentration in the root zone was 0.46, 2.3, 4.5, 6.7, 8.4 and 10.2 me cm−3 in 0.4, 2, 4, 6, 8 and 10 dS m−1 ECiw treatments, respectively. The grain production per unit evapotranspiration (
\textWP\textET\texta {\text{WP}}_{{{\text{ET}}_{\text{a}} }} ) value of 2.56 in ECiw of 0.4 dS m−1 treatment declined to 1.31 with ECiw of 2 dS m−1. The
\textWP\textET\texta {\text{WP}}_{{{\text{ET}}_{\text{a}} }} reduced to one-fifth when percolation was included in the productivity determination. Similarly, the water productivity in
respect of total dry matter production (TDM) was also reduced in different treatments. Therefore, the model predicted values
of water balance can be effectively utilized to calculate the water productivity of rice crop. 相似文献
10.
Jae Young Cho Jae Gwon Son Chang Hoon Song Seon Ah Hwang Young Min Lee Se Young Jeong Byung Yeoup Chung 《Paddy and Water Environment》2008,6(3):263-273
This study was conducted in an attempt to determine the proper nitrogen and phosphorus application levels, nitrogen split
application ratio, and application method for environmental-friendly rice production in a salt-affected rice paddy field,
which was located in the Saemangeum reclaimed tidal belt on the western coast of South Korea, between April 1, 2003 and October
10, 2004. All treatments were replicated three times in a randomized block design (5 m × 4 m plot) with 11 treatments (total
33 plots). We designed three treatments for the evaluation of reasonable application levels of nitrogen and phosphorus fertilizers
(A1–A3); five treatments to evaluate the nitrogen split application system (T1–T5); and three treatments to determine the
proper application for chemical fertilizer (M1–M3). There was no significant difference of amylose and protein content among
the application levels, application methods, and nitrogen split application ratios (P < 0.05). No significant differences in grain yield and yield components of rice were observed among the different application
levels, application methods, and nitrogen split application ratios (P < 0.05). In order to save labor in agricultural households, preserve or enhance the grain quality of rice, and reduce nutrient
losses, we determined that the optimum application level of nitrogen fertilizer was 140 kg ha−1; the application split ratio of nitrogen fertilizer at four different periods was 40% for basal fertilization, 20% for maximum
tilling stage, 30% for the panicle formation stage, and 10% for the booting stage; and the best application methods were deep
layer application and whole layer application. 相似文献
11.
Methane emission from two rice fields of Lambhvel village, Anand district, Central Gujarat, India, was measured for whole
cultivation period during pre-summer season. Along with the methane emission, soil chemistry of the two rice fields (Organic
Carbon, PO4−2 and SO4−2) was determined. The methane emission ranged from 0.10 to 0.56 mg/m2 per h, having maximum emission during noon period (11 a.m. to 1 p.m.) of the day at the Rice field-1. Besides, at rice field-2,
the methane emission ranged between 0.15 and 0.94 mg/m2 per h, having maximum peak during same period (11 a.m. to 1 p.m.) of the day. The results of the current investigation confirm
that the methane emission vary substantially between two rice fields, and suggest that soil chemistry and water level might
control the methane emission in both the rice fields and suppressed by the phosphate and sulphate concentrations. The greater
methane emission was declined with the age of rice plantation. Correlation analysis, ANOVA and F test showed that the methane emission from both the sites has positive correlation with organic carbon and negative correlation
with sulfate and phosphate content of the soil and the details of these reasons will be discussed in this paper. 相似文献
12.
Ji-Hong Jeon Chun G. Yoon Jong-Hwa Ham Kwang-Wook Jung 《Paddy and Water Environment》2005,3(2):93-101
A field experiment was performed at two Korean research sites to evaluate water and nutrient behavior in paddy rice culture
operations for 2 years. One site was irrigated with groundwater, whereas the other site was irrigated with surface water.
Both sites received average annual rainfall of about 1,300 mm, and about 70–80% of it was concentrated during July–September
coinciding with rice growing season. Although most of the nutrient outflow was attributed to plant uptake, nutrient loss by
surface drainage was substantial. The simplified computer model, PADDIMOD, was developed to simulate water and nutrient behaviors
in the paddy rice field. The model predicts daily ponded water depth, surface drainage, and nutrient concentrations. It was
formulated with a few equations and simplified assumptions, but its application and a model fitness test indicated that the
simulation results reasonably matched the observed data. It is a simple and practical planning model that could be used to
evaluate nutrient loading from paddy rice fields alone or in combination with other complex watershed models. Further validation
might be required for general application of the PADDIMOD to the simulation of paddy rice fields with various agricultural
environments. 相似文献
13.
Microorganism repair after UV-disinfection of secondary-level effluent for agricultural irrigation 总被引:1,自引:0,他引:1
Chun G. Yoon Kwang-Wook Jung Jae-Ho Jang Hyung-Chul Kim 《Paddy and Water Environment》2007,5(1):57-62
A pilot study of microorganism repair after UV disinfection was performed for agricultural reuse of secondary-level effluent
in paddy rice fields in Korea. Effluent from the bio-filter of a 16-unit apartment was used in a flow-through type UV-disinfection
system. The average concentration of suspended solids (SS) and biochemical oxygen demand (BOD) were 3.4 and 5.9 mg L−1, respectively. The mean total coliform level was in the range of 1.5 × 104 MPN 100 mL−1. Photoreactivation and dark repair were apparent at a low UV dose (6 mW s cm−2). In low-dose UV disinfection, microorganisms increased within 12 h by approximately 5 and 1% due to photoreactivation and
dark repair, respectively. This increase was not significant at a high UV dose (16 mW s cm−2). The repaired microorganisms were further inactivated, rather than reactivated, by solar irradiation, and numbers decreased
to non-detectible levels after 4 h of exposure to solar irradiation. Based on UV disinfection and repair studies, a UV dose
of 30 mW s cm−2 is recommended as sufficient to produce reclaimed water virtually free of pathogens and may be adequate for disinfection
of secondary effluent for agricultural irrigation in paddy rice culture. 相似文献
14.
Nitrous oxide emissions from paddy fields under different water managements in southeast China 总被引:2,自引:0,他引:2
Shizhang Peng Huijing Hou Junzeng Xu Zhi Mao Shalamu Abudu Yufeng Luo 《Paddy and Water Environment》2011,9(4):403-411
Water management is recognized as one of the most important factors in regulating nitrous oxide (N2O) emissions from paddy fields. In China, controlled irrigation (CI) is widely applied because it has been proved highly effective
in saving water. During the rice-growing season, the soil in CI paddy fields remains dry 60–80% of the time compared with
soil irrigated by traditional methods. This study aims to assess N2O emissions from paddy fields under CI, with traditional irrigation (TI) as the control. The cumulative N2O emission from CI paddy fields was 2.5 kg N ha−1, which was significantly greater than that from TI paddy fields (1.0 kg N ha−1) (P < 0.05). Soil drying caused substantial N2O emissions. The majority (73.9%) of the cumulative N2O emission from CI paddy fields was observed during the drying phase, whereas no substantial N2O emissions were observed when the soil was re-wetted after the drying phase. More and significantly higher peaks of N2O emissions from CI paddy fields (P < 0.05) were also detected. These peaks were observed ~8 days after fertilizer application at water-filled pore spaces (WFPS)
ranging from 78.0 to 83.5%, soil temperature ranging from 29.1 to 29.4°C, and soil redox potential (Eh) values ranging from
+207.5 to +256.7 mV. The highest N2O emission was measured 8 days after the application of base fertilizer at a WFPS of 79.0%, soil temperature of 29.1°C, and
soil Eh value of +207.5 mV. These results suggest that N2O emissions may be reduced obviously by keeping the WFPS higher than 83.5% within 10 days after each fertilizer application,
especially when the soil temperature is suitable. 相似文献
15.
Nitrous oxide (N2O) emission from flooded rice paddy fields was continuously measured by the closed chamber method at an experimental plot
in Thailand for a whole cultivation period. To characterize the N2O emission with regard to the denitrification N loss, the C2H2 inhibition method was applied. Flood water on the soil greatly suppressed the N2O emission. The N2O emission was mitigated considerably by even a thin film of the flood water. The overall average N2O emissions under flood conditions for one crop season (83 days) at the control site and the C2H2 treated site were 10.3 and 11.8 μg N m−2 h−1, respectively. The N2O emission from the C2H2 treated site was consistently higher than that from the control site and the N2O emission from both sites followed the same diurnal and seasonal variation pattern, indicating the effect of denitrification
inhibition by the supplied C2H2. The N2O emission enhanced along with temperature increase when NO3–N concentration in the soil water was above 0.4 mg N l−1 and soil temperature was above 24°C, suggesting specific temperature influence over the emission. The increase in NO3–N concentration and temperature in the soil affected only the N2O emission while the difference in the emission at the C2H2 treated site and the control site was not so much affected. It was suggested that most of the actively produced N2O under higher NO3–N concentration and temperature would likely to quickly emit to the atmosphere rather than to undergo further reduction to
N2. 相似文献
16.
Application of system of rice intensification practices in the arid environment of the Timbuktu region in Mali 总被引:1,自引:1,他引:0
Erika Styger Malick Ag Attaher Hamidou Guindo Harouna Ibrahim Mahamane Diaty Ibrahima Abba Mohamed Traore 《Paddy and Water Environment》2011,9(1):137-144
Cereal production is chronically deficit in the Timbuktu region of Mali, sufficient for only 4.5 months of annual household
consumption. Small-scale, village-based irrigation schemes, usually 30–35 ha in size, irrigated by a diesel motor pump, have
become important to improve food security in this arid region. The NGO Africare has worked during the past 12 years with farmers
in Goundam and Dire circles to establish irrigation schemes and provide them with technical assistance. In 2007, Africare
undertook a first test of the System of Rice Intensification (SRI) in Goundam circle. After farmers observed a yield of 9 t ha−1 of paddy compared to 6.7 t ha−1 in the control plot there was interest in larger scale testing of the SRI system. In 2008, Africare, in collaboration with
the local Government Agriculture Service and with support from the Better U Foundation, implemented a community-based evaluation
of SRI with 60 farmers in 12 villages. Farmers in each village selected five volunteers, who each installed both SRI and control
plots, side by side, starting the nurseries on the same day and using the same seed. For SRI plots, seedlings were transplanted
one plant hill−1 at the two-leaf stage (on average, 11.6 days old), with spacing of 25 cm × 25 cm between hills and aligned in both directions.
This allowed farmers to cross-weed with a cono-weeder, on average 2.4 times during the season. In the control plots, farmers
planted 3 plants hill−1 with seedlings 29.4 days old and spaced on average 23.7 cm, not planted in lines. Weeding was done by hand. 13 t ha−1 of organic matter was applied under SRI management, and 3 t ha−1 in the control plots. Fertilizer use was reduced by 30% with SRI compared to the control. Although alternate wetting and
drying irrigation is recommended for SRI, this was not optimally implemented due to constraints on irrigation management within
the scheme; thus water savings were only 10% compared to the control. Average SRI yield for all farmers reached 9.1 t ha−1, with the lowest being 5.4 t ha−1 and highest being 12.4 t ha−1. SRI yields were on average 66% higher than the control plots at 5.5 t ha−1, and 87% higher than the yields in surrounding rice fields at 4.9 t ha−1. Number of tillers and panicles hill−1, number of tillers and panicles m−2, and panicle length and number of grains panicle−1 were clearly superior with SRI compared to control plants. Farmers tested five varieties, all of which produced better under
SRI. The SRI system allowed for a seed reduction of 85–90%: from 40–60 kg ha−1 for the control plots to 6.1 kg ha−1 under SRI. Although production costs per hectare were 15% higher for SRI, revenue was 2.1 times higher than under the control.
Farmers were very satisfied with these results. In 2009/2010, Africare and the Government’s agriculture service worked with
over 270 farmers in 28 villages to scale up SRI practices and to test innovations, including composting techniques, optimization
of irrigation, and techniques to reduce labor requirements and production costs. The good crop performance along with other
advantages was confirmed in this third year with SRI yields of 7.7 t ha−1 (n = 130 farmers) compared to 4.5 t ha−1 in farmers’ fields. 相似文献
17.
Mustapha Ceesay 《Paddy and Water Environment》2011,9(1):129-135
Promising results from an increasing number of field evaluations of the System of Rice Intensification (SRI) conducted in
Asia and Africa indicate that African farmers could increase their rice production while lowering costs of operation and reducing
the need for water by utilizing its principles and practices. This system relies not on external inputs to raise productivity
but on alternative methods for managing rice plants and the soil and water resources devoted to their cultivation. Farmers
in sub-Saharan Africa increasingly have to cope with the impacts of adverse climate effects because water shortages and long
dry spells during the cropping season are becoming common, even in lowland rice agroecosystems. SRI management practices create
both larger rice root systems that make their plants more resistant to biotic and abiotic stresses and more conducive environments
for beneficial soil microflora and fauna to flourish. Better plant growth and development result from promoting plant–soil
synergies. Controlled fertilizer management experiments conducted with SRI practices in The Gambia have showed that grain
production can be significantly increased without higher application of inorganic fertilizer and with less requirement for
water. SRI management practices with fertilizer application at the national recommended dose produced a grain yield of 7.6 t ha−1. Water productivity was greatly increased, with 0.76 g of grain produced per kg total water input, compared to 0.10 g of
grain per kg of water when the crop was continuously flooded. Recent hikes in fuel prices and consequent rises in input costs
are making domestic rice production less attractive and importation even more attractive. Computation of production costs
showed that SRI production, not needing heavy applications of fertilizer, is economically cost-effective. Achieving yield
increases through ever-higher fertilizer applications is not economically or environmentally viable. SRI management with recommended
fertilizer applications produced a net return of $853 ha−1 compared to $853 ha−1 compared to 37 when using farmers’ present low-productivity practices. 相似文献
18.
L. Zavattaro M. Romani D. Sacco M. Bassanino C. Grignani 《Paddy and Water Environment》2006,4(1):61-66
The fertilization management of the rice crop in Piedmont was analyzed at a regional scale, and the agronomic and environmental
sustainability of the actual fertilization strategy of rice was evaluated through the analysis of its effect on the soils
and waters quality.
On average, a total amount of 127 kg ha−1 of N, 67 kg ha−1 of P2O5 and 161 kg ha−1 of K2O were supplied to the rice crop.
In most cases N and P fertilization was rather well balanced with crop removal. The N balance was in the range ±50 kg for
77% of the surface. The low concentration of N in the groundwater reflected the small N surplus. P fertilization resulted
to be smaller than removal for 53% of the surface. Nevertheless, the soil extractable P was very high, probably because of
former higher P inputs. This resulted in a high concentration in water courses and aquifers. The K fertilization was excessive
(surplus >100 kg ha−1) for 53% of the surface, but most soils showed a low K content. K is probably contributing to nutrient leaching to a great
extent.
The average soil organic matter (SOM) content of paddy fields was higher than that of normally-cultivated soils in Piedmont,
and the C/N was higher, owing to the low mineralization rate in waterlogged conditions. The SOM content was in relation with
the management of the crop residues, as the tradition of burning straw after harvest was still widespread on 65% of the paddy
surface. 相似文献
19.
Maruyama Toshisuke Noto Fumikazu Takimoto Hiroshi Nakamura Kimihito Onishi Takeo 《Paddy and Water Environment》2011,9(4):441-449
The long-term nitrogen pollution load potential (NPLPg) to groundwater from farmlands was examined in the Tedori River Basin.
The NPLPg was estimated using the difference between N in the fertilizer application rate and N outputs in crop yield at 5-yearly
intervals from 1960 to 2005. The total yearly NPLPg of 1,085 t (103 kg) in the 1960s decreased to 774 t by 1975. Thereafter,
the NPLPg gradually increased to 976 t in the 1990s, but decreased again to 369 t in 2005. The NPLPg decreased by 23% for
rice and by 37% for horticultural crops from 1960 to 2005 with an overall decrease of 34%. The NPLPg per unit area was relatively
stable over time for rice, soybean, barley, and horticultural crops, but there were significant differences among them. The
NPLPg for rice ranged from 39 to 85 kg ha−1 year−1 with an average of 65 kg ha−1 year−1 and that of the horticultural crops ranged from 273 to 357 kg ha−1 year−1 with an average of 302 kg ha−1 year−1 The significant long-term changes in the NPLPg suggest that evaluation at a specific point in time is insufficient for an
integrated assessment of groundwater pollution. 相似文献
20.
Vassilis Z. Antonopoulos 《Paddy and Water Environment》2008,6(4):387-395
A water and nitrogen balance model for the surface ponded water compartment of rice fields was developed. The model estimates
the daily ponded water depth and the daily losses and the uses of NH4–N and NO3–N in their transformation processes. The model was applied with data obtained from two rice fields during 2005 at Thessaloniki
plain in northern Greece. Significant amounts of applied irrigation water were lost with the surface runoff and deep percolation
to groundwater. The gaseous losses of nitrogen (volatilization and denitrification) and nitrogen uptake by algae were the
main processes of nitrogen reduction in the ponded water of rice fields. The study showed that the system of a rice field
is a natural system where an important amount of influent nitrogen applied by irrigation water can be reduced. These processes
decrease the possibilities of water resources contamination. 相似文献