Evaluation of comprehensive improvement for mild and moderate soil salinization in arid zone.

Sustainable development of agricultural lands in arid environments is limited by soil salinization. Comprehensive measures were conducted to completely improve soil salinization in this study. For the purpose of assessing the effect of comprehensive improvement in salinized farmland in arid zone, soil salinity at a range of soil depths, EC of subsurface pipe drainage and crop yield during crop growth period in Xinjiang, China were investigated. The results show that soil salinity decreased significantly on mildly (1-3 dS m-1) and moderately (3-6 dS m-1) salinized farmlands. The improvement in moderately salinized soil was better than that in mildly salinized soil. The average desalinization rate of mildly and moderately salinized farmland was 15% and -15.8%, respectively. The more irrigation times were, the better desalinization effect became. The EC of drainage water varied in the range of 7.53-11.16 dS m-1 and was greater than the EC of irrigation water, which showed that subsurface pipe drainage can remove soil salinity from salinized farmlands. The crop yield using comprehensive improvement increased significantly compared with the control check. The outcome of this study suggests that comprehensive measures on salinized farmland are conductive to the decrease of soil salinity and the increase of crop yield.

Analysis of the nexus between population, water resources and Global Food Security highlights significance of governance and research investments and policy priorities.

BACKGROUND: Analyses of sensitivity of Global Food Security (FS) score to a key set of supply or demand factors often suggest population and water supply as being the most critical and on which policies tend to focus. To explore other policy options, we characterized the nexus between GFS and a set of supply or demand factors including population, agricultural and industrial water uses, agricultural publications (as a surrogate for investment in agricultural research and development (R&D)) and corruption perception index (CPI), to reveal opportunities for attaining enduring GFS. RESULTS: We found that despite being the primary driver of demand for food, population showed no significant correlation with FS scores. Similarly, agricultural water use was poorly correlated with GFS scores, except in countries where evaporation exceeds precipitation and irrigation is significant. However, FS had a strong positive association with industrial water use as a surrogate for overall industrialization. Recent expansions in cultivated land area failed to yield concomitant improvements in FS score since such expansions have been mostly into marginal lands with low productivity and thus barely compensated for lands retired from cropping in several developed economies. However, FS was positively associated with agricultural R&D investments, as it was with the CPI scores. The apparent and relative strengths of these drivers on FS outcome amongst countries were in the order: industrial water-use ≈ publication rate ≈ corruption perception ≫ agricultural water use > population. CONCLUSIONS: We suggest that to enshrine enduring food security, policies should prioritize (1) increased R&D investments that address farmer needs and (2) governance mechanisms that promote accountability in both research and production value chains. © 2018 Society of Chemical Industry.

Size and stochasticity in irrigated social-ecological systems.

This paper presents a systematic study of the relation between the size of irrigation systems and the management of uncertainty. We specifically focus on studying, through a stylized theoretical model, how stochasticity in water availability and taxation interacts with the stochastic behavior of the population within irrigation systems. Our results indicate the existence of two key population thresholds for the sustainability of any irrigation system: or the critical population size required to keep the irrigation system operative, and N* or the population threshold at which the incentive to work inside the irrigation system equals the incentives to work elsewhere. Crossing irretrievably leads to system collapse. N* is the population level with a sub-optimal per capita payoff towards which irrigation systems tend to gravitate. When subjected to strong stochasticity in water availability or taxation, irrigation systems might suffer sharp population drops and irreversibly disintegrate into a system collapse, via a mechanism we dub 'collapse trap'. Our conceptual study establishes the basis for further work aiming at appraising the dynamics between size and stochasticity in irrigation systems, whose understanding is key for devising mitigation and adaptation measures to ensure their sustainability in the face of increasing and inevitable uncertainty.

Farmers' Options to Address Water Scarcity in a Changing Climate: Case Studies from two Basins in Mediterranean Chile.

Irrigated agriculture in Mediterranean areas faces tremendous challenges because of its exposure to hydroclimatic variability, increasing competition for water from different sectors, and the possibility of a climatic change. In this context, efficient management of water resources emerges as a critical issue. This requires the adoption of technological innovations, investment in infrastructure, adequate institutional arrangements, and informed decision makers. To understand farmers' perceptions and their implementation of climate change adaptation strategies with regards to water management, primary information was captured in the Limarí and Maule river basins in Chile. Farmers identified stressors for agriculture; climate change, droughts, and lack of water appeared as the most relevant stressors compared to others productive, economic, and institutional factors; revealing a rising relevance of climate related factors. While most producers perceived climate changes in recent years (92.9 %), a significant proportion (61.1 %) claim to have experienced drought, whereas only a fraction (31.9 %) have implemented a strategy to deal with this situation. Identified actions were classified in four groups: investments for water accumulation, modernization of irrigation systems, rationalization of water use, and partnership activities. Using a multinomial logit model these strategies were related to socioeconomic and productive characteristics. Results show that gender and farm size are relevant for investments, implementation and improvement of irrigation systems. For all the strategies described, access to weather information was a relevant element. The study provides empirical evidence of a recent increase in the importance assigned to climate factors by producers and adaptation options that can be supported by agricultural policy.

Cultivar Mixture Cropping Increased Water Use Efficiency in Winter Wheat under Limited Irrigation Conditions.

The effects of cultivar mixture cropping on yield, biomass, and water use efficiency (WUE) in winter wheat (Triticum aestivum L.) were investigated under non-irrigation (W0, no irrigation during growth stage), one time irrigation (W1, irrigation applied at stem elongation) and two times irrigation (W2, irrigation applied at stem elongation and anthesis) conditions. Nearly 90% of cultivar mixture cropping treatments experienced an increase in grain yield as compared with the mean of the pure stands under W0, those for W1 and W2 were 80% and 85%, respectively. Over 75% of cultivar mixture cropping treatments got greater biomass than the mean of the pure stands under the three irrigation conditions. Cultivar mixture cropping cost more water than pure stands under W0 and W1, whereas the water consumption under W2 decreased by 5.9%-6.8% as compared with pure stands. Approximately 90% of cultivar mixtures showed an increase of 5.4%-34.5% in WUE as compared with the mean of the pure stands, and about 75% of cultivar mixtures had 0.8%-28.5% higher WUE than the better pure stands under W0. Similarly, there were a majority of mixture cropping treatments with higher WUE than the mean and the better one of the pure stands under W1 and W2. On the whole, proper cultivar mixture cropping could increase yield and WUE, and a higher increase in WUE occurred under limited irrigation condition.

[Premises to the transboundary environmental crisis in the water tract on the example of water tract of the Kuban-Manych].

As a result, of the management of the irrigation system the most part of the runoff headwaters of the river Kuban was transferred to the arid plains of the Stavropol Territory, Rostov Region and Kalmykia Gravity Water via the water tract of the Kuban-Manych. This system was assumed to be supplied by pure mountain water. In fact, 3-4 class contaminated water currently passes to the water intake of the irrigation system (Nevinnomyssky channel). There is a tendency to the further deterioration in the quality of surface waters. It was determined that in the last decades in the catchment area of the upper reaches of the Kuban (Karachaevo-Cherkessia) the population was determined to increase sharply. As a result the discharge of industrial, agricultural, domestic and recreational waste into the river significantly increased. In that in catchment areas there is practically no infrastructure of the acquisition, processing and recycling of waste for the irrigation system. Intensive recreational and transport development of mountainous areas of Karachay-Cherkessia aggravates the situation and may lead to the need for deep water purification for subsequent consumption already in the vast territories of the Central Caucasus. Due to lack of the infrastructure for the water treatment in the upper reaches of the Kuban, it can lead to the serious systemic crisis. It is proposed to start to create in the catchment areas the cost-based system of recycling waste on the base of their processing by pyrolysis.

Agro-economic evaluation of water resource project--a modeling approach.

Feasibility of an irrigation project is evaluated by two criteria viz., reservoir capacity to irrigate its command area and economic returns by incremental crop production versus capital investment for dam construction. The annual water requirement of different crops in the command area is estimated and compared with the availability of water from the dam for irrigation purpose. The annual crop water requirement is estimated as the sum of evapotranspiration for crops and transmission and other losses. Evapotranspiration is estimated by modified Penman formula. Economics of crop production is analyzed by first estimating the monetary value of existing crop production under current rain fed conditions and then estimating the incremental production of irrigated command area for the proposed crop pattern. The proposed cropping pattern is prepared so as to maximize the benefit of crop production and fodder requirement while maintaining a better crop rotation to improve and maintain physical, chemical, and biological conditions of the soil. The dam is to be used for irrigation and water supply only. Command area served by this reservoir will be 76,500 ha. The existing annual agricultural return is Rs. 2995.56 lakhs and with the proposed irrigation scheme, it is estimated as Rs. 1,77,91.90 lakhs. The incremental annual return would be Rs. 1,47,96.35 lakhs i.e., 642.68% increase in annual return.