Climate change effects on paddy field thermal environment and evapotranspiration

The effect of air temperature increase from meteorological data on thermal microenvironment of irrigated paddy field is simulated using energy balance model. Statistical test was used to determine the existence of the trend in temperature change of data from meteorological stations in Indonesia. The temperature was tested to have positive trend, and it was used to generate future and past increase of temperature for the simulation. According to the simulation, the change in energy balance occurs following additional heat contributed by the increase of air temperature. The results show that irrigated paddy field seems to have function of decreasing effect of temperature increase whereas, evapotranspiration increases. However, increasing air temperature also increases temperature in paddy system, but seems to be more moderate than in nonpaddy field.     

Influence mechanism of climate change on paddy farming practices and irrigation water demand

Paddy and Water Environment - Technological and socioeconomic interventions accompanied by climate warming strongly dictate farming practices, lending a direct impact over future irrigation water...     

Conservation and contingent valuation of farming landscape amenities by visitors: A case study of terraced paddy fields in Central Japan

The contingent valuation method was used with a payment card approach to estimate visitors’ willingness to pay (WTP) to conserve a traditional agricultural landscape of terraced paddy fields in coastal rural Japan. Eighty percent of participants indicated their WTP toward a conservation fund, with estimated mean and median WTP of JPY 953.5 (~?USD $8.99) and JPY 456.4 (~?USD $4.30) per visit per person. Personal income and proximity to residence both positively influenced WTP amount; visitors’ attachment to land and loyalty were positively associated with their willingness to pay for landscape conservation. Actual conservation costs are currently mostly funded by the public municipal budget (56%) and urban volunteers (43%), but government funding sources are declining and becoming unreliable. These findings suggest that visitor donations may supplement existing funding sources for the conservation of terraced paddy field landscapes. However, farmer successors are needed for farm management to sustain traditional farming and rural communities, since a living farm and a vigorous community are essential for rural tourism.     

Development of a sustainable evaluation indicator for livestock farming system on the basis of nitrogen flow: a case study on the material flow in livestock farming along with fodder crop production and grazing on abandoned paddy fields

This study was conducted to identify the differences of characteristics of nitrogen flow on the cattle fattening breeders in different types of feeding system. Targeted breeders were classified into fodder-product type and grazing type. In both types, the nitrogen flow during livestock farming was estimated based on the inputs and outputs of materials, and summarized with following three indicators: (1) Flow-Drive Indicator (FDI), indicator for the amplified nitrogen flow per unit of external commercial materials, (2) Artificial Resources Utilization Indicator (AUI), indicator for effects of the inputs of artificial resources on nitrogen flow, and (3) Sustainability Indicator (SI = FDI/AUI), indicator for sustainability of resource utilization. As the results of nitrogen flow analysis, higher average FDI value in the grazing type (2.09) than in the fodder-product type (1.90) showed that the nitrogen from external commercial materials contributed efficiently to increase the nitrogen flow in the grazing type. The average AUI value in the fodder-product type (24.27) was clearly higher than in the grazing types (1.90). It is suggested that fodder-product type was operated by higher dependency of the inputs of utilization of artificial resources. The value of SI was less than 0.2 in the fodder-product type, and it ranged from 1.00 to 1.36 in the grazing type, respectively. It was suggested that the nitrogen flow was completely different in both types of systems, and the grazing type well utilized natural process. Moreover, by comparing the AUI and SI values, it was found that the fodder-product type was operated depending on nitrogen inputs from commercial products. In contrast, the grazing type operated well utilization of nitrogen from natural resources with less input from commercial feed.     

Assessment of nitrogen contamination of groundwater in paddy and upland fields

This study aims to assess the nitrogen contamination of groundwater in paddy and upland fields. A reactive chemical transport model PHREEQC and a variable saturated groundwater flow and transport model FEMWATER were used to evaluate the vertical transport of nitrogen compound in various soil types of paddy and upland. The shallow groundwater quality monitoring data of 2003, 2006, 2009 in the Choushui river alluvial fan, the major agriculture production area in Taiwan, were applied to support the validity of the numerical simulation findings. Results from PHREEQC and FEMWATER simulations showed that the organic-rich impermeable plow sole layer underneath the muddy layer of rice paddy can effectively reduce NO₃ ⁻ and N₂ to NH₄ ⁺ and retard the movement of NH₄ ⁺. However, in the upland field which has no plow sole layer, the NH₄ ⁺ can move easily to the shallow aquifer and contaminate the groundwater. The spatiotemporal distribution of NO₃ ⁻–N and NH₄ ⁺–N in the Choushui river alluvial fan revealed that high nitrate–N contamination areas were located mainly in the upland field of the proximal fan, where the granular unconfined aquifer was vulnerable to surface contaminants. Moreover, the unconfined nature of the aquifer allows the oxidization of NH₄ ⁺ to NO₃ ⁻ and accelerates the plume movement. High ammonium–N concentration areas were mostly dispersed in the distal-fan area where upland planting and aquacultural farming were prevailed. The high NH₄ ⁺–N found in the northern Choushui river alluvial fan was attributed to the alternative planting of rice and upland crops, and the plow sole layer was broken to maintain the quick drainage upland crop needs.     

The impact of salinity on paddy production and possible varietal portfolio transition: a Vietnamese case study

Paddy and Water Environment - Increasing soil salinisation is an environmental stressor that causes significant reduction in crop productivity and increases the risk of farming and hence reduces...     

Study on agricultural benefits by increasing capacity of water ponds: a case study at Taoyuan paddy fields

In Taiwan, agricultural water is frequently reduced or suspended for reallocation of water resources during drought. To cope with such a situation, the irrigation district of the Shihmen Reservoir in the northern Taiwan fully utilizes the functions of water ponds to regulate water resources, so that industrial and domestic water demands can be met. Constructing new water ponds is indeed able to increase water storage for irrigation. However, when it is compared with the method of dredging or excavating the existing water ponds, constructing new water ponds is not easily accepted by the public because of environmental protection and land acquisition. Dredging water ponds is adopted to obtain a larger storage capacity, so that more flexibility may be acquired in water allocation during drought. Furthermore, it is more practical from engineering point of view. This study presents a formulation of the pond-dredging problem for an irrigation system. The formulation is implemented as optimization programs and applied to the area irrigated by the eighth lateral of the Taoyuan Irrigation Association. The irrigation area is a paddy field of 2,283.8 hectares and consists of 32 water ponds storage capacity of which is analyzed as dredging is conducted. Two models are presented; the first minimizes the water extracted from the Reservoir in a cropping season; while the second maximizes agricultural financial net benefits. Various allowable dredging ratios are used in the two models for different case studies. The first model shows that the water supplied by the Reservoir decreases as the ratio increases, and it reaches the minimum (2,520.3?×?10⁴m³) when the ratio is 0.5. The second model displays that the maximum agricultural financial net benefit increases as the ratio increases and it reaches the highest value (NT$ 6,996?×?10⁴) when the ratio is 0.5, a result similar to that of the first model. However, the dredging priorities of 32 water ponds for the two models are different because of the optimization objectives. The simulation results provide references to the performance improvement of water ponds. With such improvement, water ponds can possess an optimal capacity, and an optimal regional water allocation during drought can be achieved.     

Participatory planning and monitoring of protected landscapes: a case study of an indigenous rice paddy cultural landscape in Taiwan

Paddy and Water Environment - Landscapes can be regarded as ‘a culture–nature link.’ Many examples of ‘living’ landscapes in the world are rich in natural and cultural...     

Erosion of irrigation facilities in Cambodia paddy farming region and the measures for protection

Paddy and Water Environment - This study investigates the erosion condition of irrigation earth structures and determines the measures for erosion protection in Cambodia paddy farming regions. Most...     

Effects of agri-environmental and organic rice farming on yield and macrophyte community in Mediterranean paddy fields

The Ebro Delta (Catalonia, Spain) is one of the largest wetland areas in the Mediterranean with 65% of its area occupied by rice fields. Because of the crucial role of rice fields in biodiversity and the regional economy, it is essential to find an optimum equilibrium between wetland conservation and rice productivity. The environmental and agronomic effects of three cropping systems with different degrees of farming intensity (organic, agri-environmental scheme and conventional) were assessed. The three cropping systems mainly differed in the use of agrochemicals, type of fertilizer and winter flooding. A 3-year field study was conducted in which agronomic performance and diversity and dynamics of macrophyte community in rice fields were assessed. Agri-environmental system yielded the same as the conventional one, whereas organic system significantly reduced grain yield. Biomass of weeds and macrophytes was the main contributor to yield decline. Both organic and agri-environmental systems, through winter flooding, promote the ecological succession and temporal heterogeneity of the macrophyte community in rice fields, whereas less impact on macrophyte diversity was observed. Filamentous algae were the most abundant group irrespective of the cropping system, followed by Chara vulgaris, Najas minor and Lemna minor in conventional, organic and agri-environmental systems, respectively. The environmental and agronomic benefits of winter flooding are discussed along with the current limitations of organic farming and suggested measures to make it agronomically feasible. This discussion is done under an integrative approach in which the agri-environmental legislation for the last 20 years is examined.     

Comparison of steady- and unsteady-state drainage equations for determination of subsurface drain spacing in paddy fields: a case study in Northern Iran

In Northern Iran paddy fields, waterlogging is a serious problem. Provision of subsurface drainage seems to be a prerequisite for optimal crop production. Considering specific characteristics of the paddies, application of a suitable equation for planning of subsurface drainage systems is of great importance. In this study, five steady-state equations including Hooghoudt, Kirkham, Dagan, Ernst, and Ernst–Hooghoudt; and three unsteady-state equations including Glover–Dumm, Van-Shilfgard, and De-zeeuw–Hellinga were implemented to compute drain spacing. Required field data were obtained from 52 ha of paddy fields of “Haraz Human-Agriculture Resources Development Center,” located in Mazandaran province of Iran. The computed drain spacings were evaluated using dynamic equilibrium concept and DRAINMOD model. The minimum and maximum drain spacings were found to be 26 and 63 m corresponding to Glover–Dumm and Ernst equations, respectively. Based on the dynamic equilibrium concept, the averages of the computed water table depths for the drain spacings obtained by the unsteady-state equations were 0.5–0.63 m as compared with those obtained by the steady-state methods which were in the range of 0–0.43 m. According to the DRAINMOD model simulations, the maximum relative yield was 80.2 % which was obtained when the drain spacing was 26 m and it reduced to 73.5 % when the drain spacing was increased to 63 m. The computed drain spacings suggested by the unsteady-state equations were found to be more suitable than those obtained from the steady-state equations for the study area.     

Climate‐change effects and adaptation options for temperate pasture‐based dairy farming systems: a review

Temperate pasture‐based dairy farming systems with low input of supplementary feed are vulnerable to changes in climate through alterations in feed supply and nutritive value. Although current systems in New Zealand (NZ) and southeast Australia have been successful in adapting to variable weather conditions, they will need to undergo further changes to continue to profit in the future. This review describes predicted changes in climate in NZ and southeast Australia, likely effects on the feedbase used in the pasture‐based dairy industry and the flow‐on effect on milk‐solids production and profitability. Potential adaptation options that will allow farmers to take advantage of new opportunities and minimize any negative impacts of climate change are also identified. For example, in many regions, annual pasture production is predicted to increase due to carbon dioxide fertilization and warmer temperatures during winter/spring. Production may decline, however, in regions with either reduced rainfall or severe flooding. Should this occur, farmers could strategically use supplementary feed, reduce stocking rates, irrigate or sow alternative plant species with greater drought tolerance. Pasture‐based dairy systems have high levels of adaptive capacity, and there are opportunities to continue to improve production efficiencies particularly where rainfall change is small. Further investigation into possible adaptation options is required to determine their impact on milk‐solids production and profitability, as well as to identify additional options.     

The long-term effects on upland sheep production in the UK of a change to extensive management

Extensification (a reduction in fertilizer inputs and stocking rate of grassland) is seen as one way of increasing the conservation value and of reducing the environmental impact of upland sheep production in the UK, but little is known about the consequences of such a change. This study determines the changes in animal production over ten years following the introduction of four extensive grazing management strategies to perennial ryegrass/white clover pastures at two upland sites. Fertilizer‐free treatments were maintained with sward heights of: 4 cm (treatment 4/4U) or 8 cm (8/8U) during the whole of the grazing year, 4 cm during summer and 8 cm during autumn (4/8U) and 8 cm during summer and 4 cm during autumn (8/4U). A control treatment that received 140 kg N ha^?1 year^?1 was also maintained with a sward surface height of 4 cm (4/4F). Scottish Blackface sheep grazed all treatments. The 4/4F treatment carried the greatest number of animals (3746 grazing days ha^?1 year^?1); the 4/4U and the 8/8U treatments carried 0·73 and 0·43 of this number respectively. The number on the 4/8U treatment was similar to that on the 4/4U while the 8/4U treatment carried 1·41 of that on the 8/8U treatment (0·61 of 4/4F). Mean individual animal performance was greatest on the 8 cm swards and tended to be lowest on the 4/4F treatment. However, the 4/4F treatment produced the greatest live weight of lamb (623 kg ha^?1 year^?1) with the 4/4U producing 0·77, and the 8/8U producing 0·55, of this amount. Although there was year‐to‐year variation in agricultural output, it was concluded that the lower levels of sheep production that result from a change to extensive systems of grazing management can be maintained for at least 10 years.     

Influence of overplanting paddy rice on irrigation water delivery performance: a case study in the Dakalt branch canal,Nile Delta of Egypt

In the North Nile Delta of Egypt, the impacts of overplanting paddy rice on water delivery performance have not been discussed quantitatively. Further, the amount of water that could have been saved if farmers would follow the planned area is unknown. In this study, water delivery performance was assessed by comparison of actual paddy rice planting and the government’s planned conditions. For both conditions, performance indicators relating to adequacy, equity, and dependability were analyzed across six locations in conjunction with the branch canal water level in 2013 and 2014. Based on the difference between the actual water supply and planned water demand, the amount of water that could have been saved for downstream uses was calculated. The average adequacy for the investigation period was good at one location, fair at 2 locations, and poor at 3 locations in both years. Further, adequacy under both actual and planned conditions was poor in late July at all locations. The planned adequacy and dependability downstream and equity among locations improved compared to the actual condition in both years. Under the condition that paddy rice area is the upper limit planned by the government, about 12.3% and 9.6% of water could be potentially saved in each year. The difference between actual and planned water delivery performance is caused by the branch canal’s low water level. Control of overplanting paddy rice and coordination of water distribution among water user associations would improve stable water level in the canal and, eventually, water delivery performance.

     

陆地棉自然群体纤维强度性状的全基因组关联分析

纤维强度是衡量棉花纤维品质的重要指标之一。了解棉纤维强度形成的遗传基础对棉花纤维品质的遗传改良具有重要的指导意义。本研究利用83份纤维强度差异显著的陆地棉材料,采用广义线性模型（General linear model, GLM）,对5个环境的纤维强度及最佳线性无偏估计值（Best linear unbiased prediction,BLUP）进行全基因组关联分析（Genome-wide association study,GWAS）。结果表明,各环境纤维强度基本符合正态分布,且存在丰富的变异,变异系数为5.55%～8.44%,广义遗传力达到88.67%。GWAS共检测到19个稳定的显著关联SNP位点,分布在A01、A06、D05、D08、D10、D11和D13等7条染色体上,合并为9个数量性状位点（Quantitative trait locus, QTL）区间,其中4个QTL区间与前人定位的QTL区间重叠,其它5个QTL区间是本研究新发现的控制纤维强度性状的稳定位点。根据区间内基因的表达模式及功能注释,共筛选出4个可能与纤维强度相关的候选基因。本研究通过对棉花纤维强度进行全基因组关联分析,为棉花纤维品质性状的分子遗传改良奠定了基础。     

Optimal conjunctive use of aqua-agriculture reservoir and irrigation canal for paddy fields (case study: Tajan irrigation network,Iran)

Paddy and Water Environment - Aqua-agriculture reservoirs have been used as one of the main resources for supplying water to paddy fields, particularly under water shortage conditions. In this...     

Converting rice paddy to dry land farming in the Tai Lake Basin,China: toward an understanding of environmental and economic impacts

Water pollution is a well-known major problem in the Tai Lake Basin, China. Compared to industries and domestic sewage, non-point pollution from agriculture is more difficult to detect, measure, and control. Therefore, a range of policies has been formulated, among which is that of ‘adjustment of the planting structure.’ However, this policy during implementation has been used to simply convert paddy fields to dry land and food crops to cash crops. More surprisingly, to date, no research has provided evidence that such an agricultural land-use change contributes to the reduction of agricultural nutrient pollution. Based on an extensive farm survey, this research finds that conversion of rice paddy to dry land farming has not generated a positive effect on nutrient pollution control. It is estimated that nitrogen runoff from agricultural land has increased by 11 %, while phosphorus runoff has increased more than two times since land-use patterns changed, as farmers are inclined to apply more fertilizer on dry land than in paddy fields. However, this agricultural land-use change is economically effective as land-use conversion increases the net profits of farming in a significant way. It is demonstrated that, compared to environmental concerns, economic considerations are seen to have greater benefits after such an adjustment in the planting structure. These findings have important implications for policy making by local authorities in their efforts to improve environmental management and pollution control in their territories.