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1.
The goal of this study was to investigate land use changes in urban and peri-urban Hyderabad and their influence on wastewater irrigated rice using Landsat ETM + data and spectral matching techniques. The main source of irrigation water is the Musi River, which collects a large volume of wastewater and stormwater while running through the city. From 1989 to 2002, the wastewater irrigated area along the Musi River increased from 5,213 to 8,939 ha with concurrent expansion of the city boundaries from 22,690 to 42,813 ha and also decreased barren lands and range lands from 86,899 to 66,616 ha. Opportunistic shifts in land use, especially related to wastewater irrigated agriculture, were seen as a response to the demand for fresh vegetables and easy access to markets, exploited mainly by migrant populations. While wastewater irrigated agriculture contributes to income security of marginal groups, it also supplements the food basket of many city dwellers. Landsat ETM + data and advanced methods such as spectral matching techniques are ideal for quantifying urban expansion and associated land use changes, and are useful for urban planners and decision makers alike.  相似文献   

2.
This study proposes a safe method for the disinfection of wastewater destined for reuse in urban agriculture. It also discusses the year-round production of fresh vegetables in confined urban spaces, using sustainable practices that involve the recycling and reuse of waste while at the same time saving water. To address the aforementioned problems, this study aimed to determine the efficiency of applying organoponic techniques to urban crops, using selected organic compounds and recyclable solid waste products, plus home-made organic fertilizers and treated wastewater. The results obtained demonstrate that in addition to disinfecting the wastewater, ozone contributes oxygen and nutrients to the soil, thereby reducing the need for chemical fertilizers. Ozone also reduces the risk of infection by eliminating highly pathogenic micro-organisms, and increases the rate of plant growth such as: radishes (Raphanus sativus L.), tomatoes (Lycopersicum esculentum), spearmint (Mentha piperita), camomile (Matricaria recutita), Romaine lettuce (Lactuca sativa) and Chinese cabbage (Brassica rapa). Great benefits can therefore be derived from employing these urban agriculture techniques because, in addition to putting to good use waste products that are generated by the ton, these techniques also produce quality food plants that are 100% organic.  相似文献   

3.
《Agricultural Systems》2005,83(2):223-224
The objective of this paper is to examine the impacts of terminating rice [Oryza sativa] irrigation earlier than usual. One straightforward result of this would be the associated cost savings (≈$10 ha−1 per irrigation or more with deep wells) without placing a value on the water itself. However, another option exists for some farms. An assumption is that the typical farm will be constrained from irrigating all of the soybean [Glycine max (L.) Merr] crop due to constraints in any or all of water supply, pumping capacity, and labor availability. In these cases, a portion of the land in soybean production would be non-irrigated for the first part of the growing season. This study explores the possibility of transferring irrigation water to the soybean crop after the needs of the rice crop are met. If rice and soybean planting dates are planned optimally, this partial irrigation can lead to substantial soybean yield improvements and therefore a more profitable rice/soybean production system. On average, across a 41 year period, net revenue gains from partially irrigating the soybean crop were consistently positive, ranging from $41 to $458 ha−1. While these numbers are interesting, the reader is cautioned that the results are based on simulation models and therefore the marginal analysis results are more realistic. On clayey and silt loam soils at Keiser and Stuttgart, respectively, the change in returns for moving from the least to the most water saving rice irrigation strategy was $190 and $99 ha−1, respectively. In addition, for any given year, financial losses are typically restricted to the irrigation setup costs of $17 ha−1. The irrigation termination strategies therefore show high economic potential with little risk of loss.  相似文献   

4.
Clean water has become one of the main limiting factors in agricultural food production in Europe, especially for countries around the Mediterranean, who now face more severe and frequent seasonal water shortages. In order to overcome water shortages the European Water Framework Directive encourages and promotes the use of treated urban wastewater in agriculture. However, the use of poor quality water in agriculture poses potential health risks. The application of wastewater through subsurface drip irrigation lines could possibly overcome public health concerns by minimizing contact with wastewater by farmers, farm workers but it is uncertain if the risk for consumers of wastewater irrigated produces would be acceptable. The objective of the current study was therefore to assess whether subsurface irrigation of potatoes with low quality water was associated with higher food safety and reduced human health risks as compared with surface irrigation. The microbial quality of soil and potatoes irrigated by sprinkler, furrow and subsurface drip irrigation, using treated urban wastewater, canal water and tap water were compared at experimental sites near Belgrade, Serbia and in Bologna, Italy. Water, soil and potato samples were collected from March 2007 to September 2008 and their faecal contamination estimated by enumeration of the faecal indicator Escherichia coli. In addition, water and potatoes in Italy were analysed for the presence of helminth eggs, another important indicator of faecal pollution. A quantitative microbial risk assessment (QMRA) model combined with Monte Carlo simulations was used to assess whether the different irrigation practices and associated health risks complied with guidelines set by the World Health Organization (WHO). The study found low levels of E. coli in irrigation water (Italy mean value: 1.7 colony forming units (cfu)/ml and Serbia 11 cfu/ml), as well as in soil (Italy mean: 1.0 cfu/g and Serbia 1.1 cfu/g). Similar low concentrations of E. coli were found on potatoes (Italy mean: 1.0 cfu/g and Serbia 0.0 cfu/g). The vast majority (442/516) of the collected different samples were free of E. coli. No helminth eggs were found in any types of irrigation water or on the surface of potatoes. The risk assessment models found the use of treated wastewater to exceed the levels of risks for gastro-intestinal disease (1.0 × 10−3 disease risk) as recommended by the World Health Organization (WHO) for the accidental ingestion of soil by farmers (Serbia: 0.22 and Italy: 5.7 × 10−2). However, samples that exceeded disease risks set by the WHO were collected before initiation of wastewater irrigation and were limited to a few numbers of samples, which would indicate environmental contamination not linked to irrigation practice. Disease risk from consumption of potatoes in Italy and in Serbia was found to be within acceptable levels. No relationship was found between E. coli concentrations in irrigation water, soil and produce. Similar lack of association was found for E. coli findings in sprinkler, furrow or subsurface drip irrigated soils and produce. This indicates that subsurface drip irrigation can be practiced while ensuring food safety and protecting the health of consumers and farmers.  相似文献   

5.
Rice (Oryza sativa L.) provides a life support system to millions of resource-poor farmers in rainfed environments; however, yields are very low because of various biotic and abiotic stresses. Submergence caused by typhoons and floods is one of the major reasons for production losses. Because of the complexity of these ecosystems, the breeding framework necessitates adequate feedback and a more in-depth understanding of the ecological and socioeconomic conditions in these flood-prone areas. Within this purview, this study validated the performance in farmers’ fields of lines with the SUB1 gene that confers tolerance of submergence for up to two weeks. The SUB1 gene was incorporated through marker-assisted backcrossing, MABC. The evaluation was conducted through participatory approaches to gain understanding of the risks as well as farmers’ preferences for these varieties. A baseline survey of 658 farm households accomplished during 2008, focus group discussions, key informant interviews, and adaptability trials were conducted, with focus on farmers commonly affected by submergence in four Southeast Asian countries: the Philippines, Lao PDR, Indonesia, and Southern Viet Nam. The study further examined farmers’ criteria in evaluating new varieties through the participatory varietal selection (PVS) process. Results showed that varying conditions of submergence can influence farmers’ criteria and preferences for rice cultivars. Depending on the timing of flood with respect to growth stage, shorter duration and shallow flashfloods can result in less than 10% production losses while deeper and stagnant water with two weeks’ duration and >100 cm depth can cause damage ranging from 40% to 77%. Major findings of PVS trials and preference analysis indicated that farmers prefer rice cultivars that are tolerant of submergence, have early to medium maturity relative to their commonly grown varieties, are resistant to pests and diseases, and are resistant to lodging, among other traits. To enhance adoption, male and female farmers should be involved in the evaluation process. The results of this study can contribute to enhancing breeding programs to develop appropriate varieties that reduce production losses, improve income, and ultimately reduce poverty incidence in submergence-prone areas.  相似文献   

6.
Conservation tillage systems generally improve soil organic C (SOC), plant available water capacity (PAWC), aggregation and soil water transmission. A field experiment was conducted for 4 years (2001-2002 to 2004-2005) to study tillage (conventional tillage (CT) and zero tillage (ZT)) systems. The selected irrigation treatments were at four levels (I1: pre-sowing (PS), I2: PS + active tillering (AT)/crown root initiation (CRI), I3: PS + AT/CRI + panicle initiation (PI)/flowering (FL), and I4: PS + AT/CRI + PI/FL + grain filling (GF)), applied at the critical growth stages on rice (Oryza sativa L.) and wheat (Triticum aestivum L.). Their effects on direct seeded rice productivity and soil properties (SOC and selected physical properties) after rice and wheat harvest were investigated. Soil organic C contents after rice and wheat harvest in the 0-15 cm soil depth were higher under ZT than under CT. Soil organic C increased significantly with I2 over I1 for both crops and with I4 over I2 for the wheat crop. The PAWC was significantly higher with ZT than CT. Zero tilled and frequently irrigated plots showed enhanced infiltration characteristics (infiltration rate, cumulative infiltration and sorptivity) and saturated hydraulic conductivity. Both direct seeded rice and wheat yields were not significantly different in the plots under ZT and CT. There was a significant increase in both rice and wheat yields in the plots under I2 over I1. However, water use efficiency between irrigation treatments was not significantly different. Hence, under direct seeded rice-wheat system in a sandy clay loam soil of the sub-temperate Indian Himalayas, farmers may adopt ZT with two irrigations in each crop for optimum resource conservation.  相似文献   

7.
The challenges of wastewater irrigation in developing countries   总被引：1，自引：0，他引：1  
The volume of wastewater generated by domestic, industrial and commercial sources has increased with population, urbanization, improved living conditions, and economic development. The productive use of wastewater has also increased, as millions of small-scale farmers in urban and peri-urban areas of developing countries depend on wastewater or wastewater polluted water sources to irrigate high-value edible crops for urban markets, often as they have no alternative sources of irrigation water. Undesirable constituents in wastewater can harm human health and the environment. Hence, wastewater irrigation is an issue of concern to public agencies responsible for maintaining public health and environmental quality. For diverse reasons, many developing countries are still unable to implement comprehensive wastewater treatment programs. Therefore in the near term, risk management and interim solutions are needed to prevent adverse impacts from wastewater irrigation. A combination of source control, and farm-level and post-harvest measures can be used to protect farm workers and consumers. The WHO guidelines revised in 2006 for wastewater use suggest measures beyond the traditional recommendations of producing only industrial or non-edible crops, as in many situations it is impossible to enforce a change in the current cash crop pattern, or provide alternative vegetable supply to urban markets.There are several opportunities for improving wastewater management via improved policies, institutional dialogues and financial mechanisms, which would reduce the risks in agriculture. Effluent standards combined with incentives or enforcement can motivate improvements in water management by household and industrial sectors discharging wastewater from point sources. Segregation of chemical pollutants from urban wastewater facilitates treatment and reduces risk. Strengthening institutional capacity and establishing links between water delivery and sanitation sectors through inter-institutional coordination leads to more efficient management of wastewater and risk reduction.  相似文献   

8.
《Agricultural Systems》2005,85(3):289-305
A past study in Sarawak, Malaysia (Cramb, R.A., 1993. Shifting cultivation and sustainable agriculture in East Malaysia: a longitudinal case study. Agricultural Systems 42, 209–226) found among smallholder farmers a mutual buffer effect between price fluctuations in cash crops (black pepper, Piper nigrum L. and pararubber, Hevea brasiliensis M.-Arg.) and swidden or shifting cultivation of hill rice. The recent rise in international prices for black pepper provides an opportunity to test the generality of Cramb’s original findings. For about three years beginning in 1997 and concomitant with the Asian economic crisis, smallholders throughout Southeast Asia responded to the price rises by investing more labour into existing pepper gardens, as well as planting new gardens. Here, we compare the response of Iban pepper smallholders to this situation on either side of the international border separating Sarawak, Malaysia and West Kalimantan, Indonesia, with special attention to Cramb’s findings. The mutual buffering capacity of hill rice cultivation and pepper/rubber farming described by Cramb is less evident in the study communities. The primary reasons that may account for the lack of fit revolve around the extent of pepper cultivation, availability of credit or subsidy, competition with labour in hill swiddens, and presence of nearby alternatives to earn cash.  相似文献   

9.
In the valley land of North-East Hill (NEH) ecosystems of India, about 70% area under rice (Oryza sativa L.) is transplanted. Physiological attributes and yield performance of aerobic rice over conventional flood-irrigated rice need to be assessed while promoting water saving technology. A field experiment was conducted at the experimental farm, ICAR Research Complex for NEH Region, Umiam (950 m msl), Meghalaya during rainy seasons of 2006 and 2007 under aerobic and flooded conditions with aerobic rice variety collected from IRRI, Philippines. Some important high-yielding varieties (HYVs) recommended for the region were also included in the study. The objectives of this study were (i) to evaluate the influence of frequent mid-season drainage as a measure of water saving technique besides inducing the pre-conditioning effect on genotypes to withstand water stress during the subsequent growth period of crop ontogeny, (ii) to compare crop performance between aerobic and flooded rice management practices, and (iii) to identify attributes responsible for the yield gap between aerobic and flooded rice. The results revealed that the yield difference between aerobic (average yield, 1.67 t/ha) and flooded rice (average yield, 2.31 t/ha) ranged from 18.4 to 37.8% (P < 0.05) depending on varieties, highest difference being observed with rice hybrid DRRH 1. Cultivation of rice under aerobic condition resulted in 27.5% yield reduction over flooded rice. Among the yield components assessed, sink size (spikelets per panicle) contributed more to the yield and is considered to be most important factor responsible for yield gap between aerobic and flooded rice. The study suggests that, variety Sahsarang 1 with its moderate values of photosynthesis rate, transpiration rate and water use efficiency (WUE) along with higher grain yield seems to be better choice for both stress (aerobic) as well as normal (flooded) condition. Aerobic rice varieties with minimum yield gap compared to flooded rice is the key for success of aerobic rice cultivation.  相似文献   

10.
Response of timely and late seeded wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) to three levels of irrigation and four rates of nitrogen was investigated under pre-seeding irrigation. Water extraction pattern and water use of these crops varied markedly. Barley outyielded wheat by 27 and 9%, but used 9 and 21 mm less water, when one and two irrigations were given at critical stages, respectively. These results indicate the possibilities of considerable saving of water (100 mm) for barley without any decrease in grain yield and increased water-use efficiency (WUE) of wheat and barley by irrigating at critical stages as compared to irrigation at 75% depletion of available soil water (ASW). In general WUE decreased with increase in irrigation frequency and delay in seeding.Nitrogen fertilization with marginal additional water use (4–9%) increased yield linearly (45–98%) and thus increased WUE of wheat and barley. This additional water was extracted from below 60 cm depth at tensions ? 1.5 MPa and particularly in maximum growth and reproductive stages. These results suggest that barley should be preferred to wheat under medium to severe water stress and late seeding conditions.  相似文献   

11.
Oilseed and pulse crops have been increasingly used to replace conventional summer fallow and diversify cropping systems in northern high latitude areas. The knowledge of water use (WU) and its distribution profile in the soil is essential for optimizing cropping systems aimed at improving water use efficiency (WUE). This study characterized water use and distribution profile for pulse and oilseed crops compared to spring wheat (Triticum aestivum L.) in a semiarid environment. Three oilseeds [canola (Brassica napus L.), mustard (Brassica juncea L.) and flax (Linum usitatissimum L.)], three pulses [chickpea (Cicer arietinum L.), dry pea (Pisum sativum L.) and lentil (Lens culinaris Medik.)], and spring wheat were seeded in removable 100 cm deep × 15 cm diameter lysimeters placed in an Aridic Haploboroll soil, in southwest Saskatchewan in 2006 and 2007. Crops were studied under rainfed and irrigated conditions where lysimeters were removed and sampled for plant biomass and WU at various soil depths. Wheat yields were greater than pulse crop yields which were greater than oilseed yields, and WUE averaged 4.08 kg ha−1 mm−1 for pulse crops, 3.64 kg ha−1 mm−1 for oilseeds, and ranged between 5.5 and 7.0 kg ha−1 mm−1 for wheat. Wheat used water faster than pulse and oilseed crops with crop growth. Pulse crops extracted water mostly from the upper 60 cm soil depths, and left more water unused in the profile at maturity compared to oilseeds or wheat. Among the three pulses, lentil used the least amount of water and appeared to have a shallower rooting depth than chickpea and dry pea. Soil WU and distribution profile under canola and mustard were generally similar; both using more water than flax. Differences in WU and distribution profile were similar for crops grown under rainfall and irrigation conditions. A deep rooting crop grown after pulses may receive more benefits from water conservation in the soil profile than when grown after oilseed or wheat. Alternating pulse crops with oilseeds or wheat in a well-planned crop sequence may improve WUE for the entire cropping systems in semiarid environments.  相似文献   

12.
Summary Wastewater from a fertilizer manufacturing plant in southern Idaho was pumped into a storage impoundment during the winter months and stored for irrigating and fertilizing agricultural crops the next summer. Analyses of water samples from the impoundment taken monthly showed the following mean annual nutrient concentrations: Total Kjeldahl Nitrogen (TKN) 94, NH 4 + -N 61, NO 3 – -N 8, total P 17, ortho P 15, and K 17 mg/L. The impoundment surface area averaged 10.5 ha with a maximum pond volume during the year of 362,000 m3. Accumulated nutrients in the impounded wastewater available for irrigating and fertilizing agricultural crops at the beginning of the growing season was TKN 30.2, NH 4 + -N 23.2, NO3-N 4.3, total P 9.7, and K 6.2 metric tons. Nitrification in the pond was minimal. Redox potentials were between 480 and 500 mv at all depths and locations measured in the pond in the summer and denitrification was minimal. The redox potential indicated that the water was near oxygen saturation.  相似文献   

13.
Crop consumptive water use and productivity are key elements to understand basin water management performance. This article presents a simplified approach to map rice (Oryza sativa L.) water consumption, yield, and water productivity (WP) in the Indo-Gangetic Basin (IGB) by combining remotely sensed imagery, national census and meteorological data. The statistical rice cropped area and production data were synthesized to calculate district-level land productivity, which is then further extrapolated to pixel-level values using MODIS NDVI product based on a crop dominance map. The water consumption by actual evapotranspiration is estimated with Simplified Surface Energy Balance (SSEB) model taking meteorological data and MODIS land surface temperature products as inputs. WP maps are then generated by dividing the rice productivity map with the seasonal actual evapotranspiration (ET) map. The average rice yields for Pakistan, India, Nepal and Bangladesh in the basin are 2.60, 2.53, 3.54 and 2.75 tons/ha, respectively. The average rice ET is 416 mm, accounting for only 68.2% of potential ET. The average WP of rice is 0.74 kg/m3. The WP generally varies with the trends of yield variation. A comparative analysis of ET, yield, rainfall and WP maps indicates greater scope for improvement of the downstream areas of the Ganges basin. The method proposed is simple, with satisfactory accuracy, and can be easily applied elsewhere.  相似文献   

14.
《Agricultural Systems》2003,76(3):913-927
Because of growth and development in agricultural areas at the rural–urban interface, a variety of farmer adaptations have been identified. While exiting from farming or entrepreneurial adaptations that tap urban markets are frequently identified responses, farmers might also attempt to develop social capital, or neighborly relations, with nonfarm neighbors to mitigate social constraints created by nonfarmer concerns at the rural–urban interface. In a case study of an agricultural region within a large metropolitan area, this research reports data from a survey of farm and nonfarm residents (N=620). The analysis operationalizes the concept of social capital, nonfarmer trust of farmers and frequency of nonfarmer interaction with farmers, to determine whether these social relations have a discernable impact on nonfarmer support or tolerance of agriculture. Results reveal a relationship, indicating that support and tolerance of agriculture is stronger when nonfarmers report the existence of social capital with farmers. These findings have implications for farm operator adaptations as well as community capacity to preserve or develop local agriculture.  相似文献   

15.
四川省农村垃圾与污水处理现状调研与分析   总被引：3，自引：0，他引：3  
为了解四川省城乡环境综合整治效果,以问卷调查的形式对四川省10个城市、19个村、进行实地走访调研.得到并分析了四川省农村垃圾与污水处理现状、农民环境保护意识的转变及农村沼气的发展现状,为科学管理和再次合理规划四川城乡环境提供了必要的数据支持.  相似文献   

16.
《Agricultural Systems》2007,92(1-3):318-333
This paper presents an econometric analysis of the influence of soil fertility status on productivity and resource use in rice production utilizing survey data from 21 villages in three agro-ecological regions of Bangladesh. Detailed crop husbandry input–output data were collected from 380 paddy rice (Oryza sativa) farmers. Data collected included fertilizer, pesticide, labour, animal power services, irrigation, farm capital assets and rice yield. The soil fertility status in each region was determined by analysis of soil organic carbon, available nitrogen, phosphorus and potassium concentration. Analysis was based on a profit function, where the selected soil fertility parameters were incorporated as yield controlling variables. Results revealed that soil fertility has a significant influence on both productivity and farmers’ resource allocation decisions. Output supply was significantly higher in fertile regions and input use was significantly lower. This observation indicates that in policy terms technological initiatives should be targeted at measures to identify areas of lower soil fertility so that inherent soil-based productivity restrictions can be minimized. In part this will be facilitated by the transfer of indigenous knowledge from farmers in higher productivity areas, thus increasing rice production and raising the competitiveness of Bangladeshi rice farmers.  相似文献   

17.
The increasing cost and scarcity of water for irrigation is placing pressure on Australian dairy farmers to utilize water more efficiently, and as result, water use efficiency (WUE) of forages is becoming an important criterion for sustainable dairy production. This study was conducted to identify more water use efficient forage species than the dominant dairy forage, perennial ryegrass (Lolium perenne L.). Seventeen annual forage species were investigated under optimum irrigation (I1) and two deficit irrigation treatments (nominally 66 and 33% of irrigation water applied to the optimal level), over 3 years at Camden, NSW, on a brown Dermsol in a warm temperate climate. Forages with the highest yield generally had the highest WUEt (total yield/evapotranspiration). Under optimal irrigation, there was a three-fold difference in mean annual WUEt between forages, with maize (Zea mays L.) having the highest (42.9 kg ha−1 mm−1) and cowpea (Vigna unguiculata (L.) Walp.) the lowest (13.5 kg ha−1 mm−1), with 11 of the forage species having a greater WUEt than perennial ryegrass. The ‘harvested’ forages maize, wheat, triticale (Triticosecale rimpaui Wittm.) and maple pea (Pisum sativium L.) generally had higher mean WUEt (26.7-42.9 kg ha−1 mm−1) than the remaining forages which were defoliated multiple times to simulate grazing (13.5-30.1 kg ha−1 mm−1). The reduction in annual WUEt in response to deficit irrigation was greatest for the warm season forages with up to 30% reduction for maize, while most of the cool season annuals were not significantly affected by deficit irrigation at the levels imposed. In order to maximize WUEt of any forage, it is necessary to maximize yield, as there is a strong positive relationship between yield and WUEt. However, while WUEt is an important criterion for choosing dairy forages, it is only one factor in a complex system. Choice of forages must be considered on a whole farm basis and include consideration of yield, nutritive value, cost of production and risk.  相似文献   

18.
Rice (Oryza sativa L.) root systems play an important role in uptake of water and nutrients from soil. A 4-year field experiment was conducted to determine the effects of different nutrient and water regimes on root growth by measuring the root diameter, root density, and root activity. Three nutrient regimes were used: (i) combined application of chemical fertilizers with farmyard manure (CM), (ii) integrated use of chemical fertilizers and wheat straw (CS), (iii) chemical fertilizers only (CK). Two soil moisture regimes included continuous waterlogging (CWL) and alternate wetting and drying (AWD). Incorporation of organic sources into paddy soil markedly improved root morphological characteristics of rice plant. In the alternate wetting and drying (AWD), root length density (RLD), and root weight density (RWD) for organic fertilization treatments (CS and CM) increased by 30 and 40%, respectively, as compared with the sole chemical fertilization (CF). Relative to root activity, CWL had adverse effects on root active absorption area (AAA), root oxidation ability of alpha-naphthylamine (α-NA) (ROA), and root surface phosphatase (RSP) of rice plants treated by integrated application of organic and inorganic fertilizers. In particular for the CM treatment, the AAA, ROA, and RSP of rice plants by the continuous flooding decreased by 22, 28, and 35%, respectively, compared to the alternately flooded regime. In the water regime of AWD, incorporation of organic manure significantly increased N, P, and K uptake by rice plants and facilitated the allocation and transfer of nutrient elements, especially P to rice ears and grains. This resulted in significant increases in the filled grains panicle−1, 1000-grain weight and grain yield. The beneficial effects of integrated use of organic and mineral fertilizers on grain yield were significantly (P < 0.05) decreased by the water regime of CWL.  相似文献   

19.
The environmental impact of irrigating a maize field with weathered olive mill wastewater (OMW) for 5 years was assessed. The use of the weathered OMW added the following concentrations of nutrients to the field: 11.8 t/ha/yr carbon, 1033 kg/ha/yr total nitrogen, 23.8 kg/ha/yr phosphorous and 4161 kg/ha/yr potassium. The maize field received 6 times more nitrogen, 50 times more potassium and 2 times less phosphorous than the recommended fertilization rates. The presence of carbon increased microbial activity for organic nitrogen breakdown and the decomposition rate of organic nitrogen. No significant increase was observed of heavy metal accumulation in the soil. Electrical conductivity in the soil remained below the salinization threshold. No direct exposure values were exceeded. No impact on groundwater quality was observed. Irrigation of crops like maize with weathered OMW could be part of a viable decentralized solution for olive mill wastewater use in areas with low organic matter and high irrigation demand.  相似文献   

20.
Soil moisture availability is the main limiting factor for growing second crops in rainfed rice fallows of eastern India. Only rainfed rice is grown with traditional practices during the rainy season (June–October) with large areas (13 m ha−1) remaining fallow during the subsequent dry season (November–March) inspite of annual rainfall of the order 1000–2000 mm. In this study an attempt was made to improve productivity of rainfed rice during rainy season and to grow second crops in rice fallow during dry (winter) season with supplemental irrigation from harvested rainwater. Rice was grown as first crop with improved as well as traditional farmers’ management practices to compare the productivity between these two treatments. Study revealed that 87.1–95.6% higher yield of rice was obtained with improved management over farmers’ practices. Five crops viz., maize, groundnut, sunflower, wheat and potato were grown in rice fallow during dry (winter) season with two, three and four supplemental irrigations and improved management. Sufficient amount of excess rainwater (runoff) was available (381 mm at 75% probability level) to store and recycle for supplementary irrigation to second crops grown after rice. Study revealed that supplemental irrigation had significant effect (P < 0.001) on grain yield of dry season crops and with two irrigation mean yields of 1845, 785, 905, 1420, 8050 kg ha−1 were obtained with maize (grain), groundnut, sunflower, wheat and potato (tuber), respectively. With four irrigations 214, 89, 78, 81, 54% yield was enhanced over two irrigations in respective five crops. Water use efficiency (WUE) of 13.8, 3.35, 3.39, 5.85 and 28.7 kg ha−1 was obtained in maize, groundnut, sunflower, wheat, potato (tuber), respectively with four irrigations. The different plant growth parameters like maximum above ground biomass, leaf area index and root length were also recorded with different levels of supplemental irrigation. The study amply revealed that there was scope to improve productivity of rainfed rice during rainy season and to grow another profitable crops during winter/dry season in rice fallow with supplemental irrigation from harvested rainwater of rainy season.  相似文献   

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