Long-term Agricultural Sustainability Research Articles

Building a prospective participatory approach for long-term agricultural sustainability in the Lezíria do Tejo region (Portugal)

Addressing the gaps between theory, research and practice, this paper explores a hybrid mindset of participatory action research (PAR), geoprospective and participatory geographical information system (PGIS). This approach brings together stakeholders, policy-makers and researchers – in an agricultural peri-urban region of Portugal, the Lezíria do Tejo region – to anticipate the possible changes in agricultural territories, while taking spatial dynamics into account. It uses a four-step methodology which integrates qualitative and quantitative approaches to select stakeholders’ interview areas, implement prospective workshops to engage and explore the stakeholders’ interests and encourage actions towards finding solutions for long-term agricultural sustainability in this region. The results from our study highlight that more participative approaches such as the ones developed here must be implemented towards decision-making, since they help to dispel the distrust between stakeholders, strengthen community cohesion and also contribute to build common solutions drawing upon various perspectives. From a PAR perspective, this work contributes to bridge the gap between academia and practitioners, as is shown by a willingness of the practitioners to actively participate in the research under progress.

Bulk optical characterization of dissolved organic matter from semiarid wheat-based cropping systems

Dissolved organic matter (DOM) plays a critical role in the cycling of nutrients and long-term agricultural sustainability. The composition of DOM in soil is likely altered due to management, yet there is limited knowledge on the effect of long-term cropping on DOM chemical character. Here, we characterized water extractable DOM composition along a gradient of soil organic carbon (SOC) affected by differing cropping and tillage intensity in a semiarid climate of the northern Great Plains, USA. Soil samples (0–10, 10–20, 20–30 cm) were collected from conventional till-fallow winter wheat (Triticum aestivum L.; Ftill-W), no-till spring pea/oilseed-wheat (Pisum sativum L.; Pg/O-W), and no-till continuous wheat (W-W) fields, and analyzed using UV/Vis absorbance and excitation-emission matrix fluorescence spectroscopy. The concentration of DOM decreased with depth and was significantly greater (P<0.05) under W-W or Pg/O-W than Ftill-W. The absorbance at 254 nm (Abs254), a proxy for DOM aromatic nature, indicated that aromaticity decreased with depth and lower biomass-C inputs (i.e. W-W≥ Pg/O-W ≥Ftill-W). Multidimensional parallel factor (PARAFAC) analysis revealed humic-like (C1, C2), monolignol-like (C3), and protein/tannin-like (C4) components with varying fluorescence intensities as a function of cropping system and soil depth. DOM humification, indicated by the humification index (HIX), increased significantly with depth (P<0.05) and was higher for Ftill-W (2.95) than W-W (2.61) or Pg/O-W (2.28). Overall, DOM became depleted of plant-derived constituents and was enriched by more decomposed, condensed substances in Ftill-W, as compared to W-W or Pg/O-W soils. DOM composition is strongly affected by cropping intensity and such changes are important drivers controlling SOC accretion in arable soils.

Molecular composition of soil organic matter with land-use change along a bi-continental mean annual temperature gradient

Soil organic matter (SOM) is critical for maintaining soil fertility and long-term agricultural sustainability. The molecular composition of SOM is likely altered due to global climate and land-use change; but rarely are these two aspects studied in tandem. Here we used molecular-level techniques to examine SOM composition along a bi-continental (from North to South America) mean annual temperature (MAT) gradient from seven native grassland/forest and cultivated/pasture sites. Biomarker methods included solvent extraction, base hydrolysis and cupric (II) oxide oxidation for the analysis of free lipids of plant and microbial origin, ester-bound lipids from cutin and suberin, and lignin-derived phenols, respectively. Solid-state 13C nuclear magnetic resonance (NMR) was used to examine the overall composition of SOM. Soil cultivation was found to increase the amount of microbial-derived compounds at warmer temperatures (up to 17% increase). The cultivated soils were characterized by much lower contributions of plant-derived SOM components compared to the native soils (up to 64% lower at the coldest site). In addition, cultivation caused an increase in lignin and cutin degradation (up to 68 and 15% increase, respectively), and an increase in the amount of suberin-derived inputs (up to 54% increase). Clear differences in the molecular composition of SOM due to soil cultivation were observed in soils of varying mineral composition and were attributed to disturbance, different vegetation inputs, soil aggregate destruction and MAT. A high organic allophanic tropical soil was characterized by its protection of carbohydrates and nitrogen-containing compounds. The conversion of native to cultivated land shows significant shifts in the degradation stage of SOM. In particular, cutin-derived compounds which are believed to be part of the stable SOM pool may undergo enhanced degradation with long-term cultivation and disruption of soil aggregates. On a per year basis, the total amount of cutin decreased only at the two forest sites that were converted to pasture, likely due to cutin degradation or to changes in vegetation and litter quality associated with land-use change. Overall, our study highlights that the implementation of different agricultural management practices enhances the degradation of recalcitrant SOM compounds that may become a source of atmospheric CO2 with increasing land-use and climate change.

Annual crop rotation of tropical pastures with no-till soil as affected by lime surface application

Abstract Soil acidity and low natural fertility are the main limiting factors for grain production in tropical regions such as the Brazilian Cerrado. The application of lime to the surface of no-till soil can improve plant nutrition, dry matter production, crop yields and revenue. The present study, conducted at the Lageado Experimental Farm in Botucatu, State of Sao Paulo, Brazil, is part of an ongoing research project initiated in 2002 to evaluate the long-term effects of the surface application of lime on the soil’s chemical attributes, nutrition and kernel/grain yield of peanut (Arachis hypogaea), white oat (Avena sativa L.) and maize (Zea mays L.) intercropped with palisade grass (Urochloa brizantha cv. Marandu), as well as the forage dry matter yield of palisade grass in winter/spring, its crude protein concentration, estimated meat production, and revenue in a tropical region with a dry winter during four growing seasons. The experiment was designed in randomized blocks with four replications. The treatments consisted of four rates of lime application (0, 1000, 2000 and 4000 kg ha−1), performed in November 2004. The surface application of limestone to the studied tropical no-till soil was efficient in reducing soil acidity from the surface down to a depth of 0.60 m and resulted in greater availability of P and K at the soil surface. Ca and Mg availability in the soil also increased with the lime application rate, up to a depth of 0.60 m. Nutrient absorption was enhanced with liming, especially regarding the nutrient uptake of K, Ca and Mg by plants. Significant increases in the yield components and kernel/grain yields of peanut, white oat and maize were obtained through the surface application of limestone. The lime rates estimated to achieve the maximum grain yield, especially in white oat and maize, were very close to the rates necessary to increase the base saturation of a soil sample collected at a depth of 0–0.20 m to 70%, indicating that the surface liming of 2000 kg ha−1 is effective for the studied tropical no-till soil. This lime rate also increases the forage dry matter yield, crude protein concentration and estimated meat production during winter/spring in the maize-palisade grass intercropping, provides the highest total and mean net profit during the four growing seasons, and can improve the long-term sustainability of tropical agriculture in the Brazilian Cerrado.

Using Modified Remote Sensing Imagery to Interpret Changes in Cultivated Land under Saline-Alkali Conditions

Managing the rapidly changing saline-alkali land under cultivation in the coastal areas of China is important not only for mitigating the negative impacts of such land on the environment, but also for ensuring long-term sustainability of agriculture. In this light, setting up rapid monitoring systems to assist decision-making in developing sustainable management plans is therefore an absolute necessity. In this study, we developed a new interpretation system where symbols are used to grade and classify saline-alkali lands in space and time, based on the characteristics of plant cover and features of remote sensing images. The system was used in combination with the maximum likelihood supervised classification to analyze the changes in cultivated lands under saline-alkali conditions in Huanghua City. The analysis revealed changes in the area and spatial distribution of cultivated under saline-alkali conditions in the region. The total area of saline-alkali land was 139,588.8 ha in 1992 and 134,477.5 ha in 2011. Compared with 1992, severely and moderately saline-alkali land areas decreased in 2011. However, non/slightly saline land areas increased over that in 1992. The results showed that the salinization rate of arable lands in Huanghua City decreased from 1992 to 2011. The moderately saline-alkali land southeast of the city transformed into non/slightly saline-alkaline. Then, severely saline-alkali land far from the coastal zone west of the city became moderately saline-alkaline. Spatial changes in cultivated saline-alkali lands in Huanghua City were such that the centers of gravity (CG) of severely and non/slightly saline-alkali land moved closer the coastline, while that of the moderately saline-alkali land moved from southwest coastal line to northwest. Factors influencing changes in cultivated lands in the saline-alkali ecosystem included climate, hydrology and human activity. Thus, studies are required to further explore these factors in order to build a better understanding into the relative contributions of the changes saline-alkali state on the functions of coastline ecosystems.

Effects of long-term fertilization on oxidizable organic carbon fractions on the Loess Plateau, China

The effects of long-term fertilization on pools of soil organic carbon (SOC) have been well studied, but limited information is available on the oxidizable organic carbon (OOC) fractions, especially for the Loess Plateau in China. We evaluated the effects of a 15-year fertilization on the OOC fractions (F1, F2, F3 and F4) in the 0–20 and 20–40 cm soil layers in flat farmland under nine treatments (N (nitrogen, urea), P (phosphorus, monocalcium phosphate), M (organic fertilizer, composted sheep manure), N+P (NP), M+N (MN), M+P (MP), M+N+P (MNP), CK (control, no fertilizer) and bare land (BL, no crops or fertilizer)). SOC content increased more markedly in the treatment containing manure than in those with inorganic fertilizers alone. F1, F2, F4 and F3 accounted for 47%, 27%, 18% and 8% of total organic carbon, respectively. F1 was a more sensitive index than the other C fractions in the sensitivity index (SI) analysis. F1 and F2 were highly correlated with total nitrogen (TN) and available nitrogen (AN), F3 was negatively correlated with pH and F4 was correlated with TN. A cluster analysis showed that the treatments containing manure formed one group, and the other treatments formed another group, which indicated the different effects of fertilization on soil properties. Long-term fertilization with inorganic fertilizer increased the F4 fraction while manure fertilizer not only increased labile fractions (F1) in a short time, but also increased passive fraction (F4) over a longer term. The mixed fertilizer mainly affected F3 fraction. The study demonstrated that manure fertilizer was recommended to use in the farmland on the Loess Plateau for the long-term sustainability of agriculture.

Land-use changes by large-scale plantations and their effects on soil organic carbon, micronutrients and bulk density: empirical evidence from Ethiopia

This article examines land-use changes by large-scale plantations in Ethiopia and evaluates the impacts thereof on soil organic carbon, micronutrients and bulk density. Remote sensing analysis and field research activities were undertaken at four large-scale plantation projects in Benshanguel Gumuz, Gambella, and Oromia regional states. Results show that the projects largely involved the conversion of both closed and open to closed forests and grasslands, which in turn reduced soil carbon stock and micronutrient levels and increased soil compaction. We argue that unless appropriate soil management activities and impact mitigation strategies are adopted by plantation proponents, these land-use changes will pose a serious threat to the long-term economic viability and sustainability of plantation agriculture in Ethiopia. This could undermine long-term ecosystem health and national food security.

The 4Rs for cover crops and other advances in cover crop management for environmental quality

Humans have used soil resources for thousands of years. Human use has degraded and eroded soil worldwide in ways that damage food production, biodiversity, and ecosystem services. A direct implication of soil degradation is that soil scarcity will become a critical future problem for global agricultural production. With limited new lands for cultivation worldwide and a projected increase in global population to 10 billion this century, long-term agricultural sustainability is an increasing global concern. To conserve soil, better agricultural methods that sustain the soil are needed (Montgomery 2007). Soil management must focus on regaining a balance in (1) organic carbon (C) inputs and losses, (2) soil erosion and production, and (3) release and loss of nutrients (Amundson et al. 2015). Soil does far more than just support farming and forestry. It stores C, filters water, transforms nutrients, and sustains plant and animal biodiversity by conservation of critical shrinking wildlife habitat. It is unclear how these essential processes will respond to agricultural intensification, or how they might be enhanced in tandem with farming (Banwart 2011).

Temporal Oscillation and Losses of Three Carbon Forms in a Microcatchment of NW Spain

Long-term agricultural sustainability and water quality may be threatened by inadequate land management. Carbon (C) losses at the catchment scale largely depend on land use and management practices. In “Abelar” farm (A Coruña, NW Spain), swine slurry was directly discharged during a period of about 30 years onto agricultural maize fields and rangeland under cattle production. In 1998, the agricultural fields and rangeland were planted to stands of Eucalyptus globulus. The purpose of this work was to assess the concentrations and losses of total, inorganic, and organic carbon at the outlet of a small catchment (10.7 ha) in the period from March 2007 to December 2010. Nearly 190 water samples were collected; specifically eleven in 2007, sixty-eight in 2008, fifty-six in 2009, and fifty-three in 2010. Total runoff volumes from the catchment were also measured during the 3.7-year study period. Except for a peak recorded in November 2008, total carbon values (TC) ranged from 1.51 to 6.14 mg L−1, total inorganic carbon (TIC) varied between 0.54 and 3.30 mg L−1, and total organic carbon (TOC) was between 0.38 and 2.83 mg L−1; the exception was due to an occasional pig slurry discharge occurring in 2008, which drove the greatest values of the three carbon forms. The season of the year influenced concentrations of total, organic, and inorganic carbon. Total, organic, and inorganic carbon loads exported at the catchment outlet were estimated at the monthly and yearly time scales. Overall, 10 years after planting to the forest, dissolved and total carbon losses were rather small.

Assessment of soil loss in South Korea based on land-cover type

Soil loss poses a significant threat to the long-term sustainability of hydrological systems, the environment, and agriculture. In this regard, efficient soil management relies on accurate quantification of soil loss. To this end, the Organization for Economic Cooperation and Development (OECD) standard of soil erosion, developed for agricultural areas, has been applied in many countries, including South Korea. Due to the lack of standard methods for assessing soil erosion in South Korea, the OECD standard has been applied to non-agricultural regions of Korea despite the possibility that local soil erosion characteristics may differ from those in agricultural areas. Such an approach might give erroneous information on soil loss to policy and decision makers. This study estimated soil loss for eight different land cover-types in Korea using the universal soil loss equation, and compared the results with those from the unmodified OECD soil erosion standard. Estimated soil loss differed considerably among land-cover types. The results have implications on the limitations in applying the OECD soil erosion standard to soil management in Korea. Thus, this study suggests a modified soil erosion standard for efficient soil management.

The impact of selective-logging and forest clearance for oil palm on fungal communities in Borneo.

Tropical forests are being rapidly altered by logging, and cleared for agriculture. Understanding the effects of these land use changes on soil fungi, which play vital roles in the soil ecosystem functioning and services, is a major conservation frontier. Using 454-pyrosequencing of the ITS1 region of extracted soil DNA, we compared communities of soil fungi between unlogged, once-logged, and twice-logged rainforest, and areas cleared for oil palm, in Sabah, Malaysia. Overall fungal community composition differed significantly between forest and oil palm plantation. The OTU richness and Chao 1 were higher in forest, compared to oil palm plantation. As a proportion of total reads, Basidiomycota were more abundant in forest soil, compared to oil palm plantation soil. The turnover of fungal OTUs across space, true β-diversity, was also higher in forest than oil palm plantation. Ectomycorrhizal (EcM) fungal abundance was significantly different between land uses, with highest relative abundance (out of total fungal reads) observed in unlogged forest soil, lower abundance in logged forest, and lowest in oil palm. In their entirety, these results indicate a pervasive effect of conversion to oil palm on fungal community structure. Such wholesale changes in fungal communities might impact the long-term sustainability of oil palm agriculture. Logging also has more subtle long term effects, on relative abundance of EcM fungi, which might affect tree recruitment and nutrient cycling. However, in general the logged forest retains most of the diversity and community composition of unlogged forest.

INDO-LANKA FREE TRADE AGREEMENT (FTA) AND THE ENVIRONMENTAL EFFECTS THE CASE OF LAND DEGRADATION IN SRI LANKA

Sri Lanka has implemented far- reaching trade policy reforms to improve internationalcompetitiveness of its agricultural and industrial products and trade-in services and to attractforeign direct investment (FOI) during the last two decades since the introduction of the Indo-Lanka Free Trade Agreement (FAT), there has been growing concern on its environmentalimpacts on non-plantation agriculture.This paper analyzes the FAT-induced likely environmental impacts. In particular landdegradation -induced on site effects such as loss of agricultural production and off-site effectssuch as reduction in downstream irrigated agricultural production and hydro-power generationand increasing cost of flushing downstream reservoirs, operation and maintenance cost of uplandroad network, and cost of health hazards. In this analysis an appropriately modified computablegeneral equilibrium (CGE) model of the Sri Lankan economy is used.Results show that trade policy framework of ITA in non-plantation agriculture (i.e. imposingtariff on non-plantation agriculture) does not result in likely benign on- site and off- siteenvironmental on -site and off-site environmental effects. It is suggested that ITAhave effects that are harmful to long-term sustainability of non-plantation agriculture in SriLanka.

Interactions between root hair length and arbuscular mycorrhizal colonisation in phosphorus deficient barley (Hordeum vulgare)

Phosphorus (P) limits crop yield and P-fertilisers are frequently applied to agricultural soils. However, supplies of quality rock phosphate are diminishing. Plants have evolved mechanisms to improve P-acquisition and understanding these could improve the long-term sustainability of agriculture. Here we examined interactions between root hairs and arbuscular mycorrhizal (AM) colonisation in barley (Hordeum vulgare L.). Barley mutants exhibiting different root hair phenotypes, wild type barley and narrowleaf plantain (Plantago lanceolata L.) were grown in the glasshouse in P-sufficient and P-deficient treatments and allowed to develop AM colonization from the natural soil community. Plants were harvested after 6 weeks growth and root hair length, AM-fungal colonisation, shoot biomass and P-accumulation measured. Under P-deficient conditions, root hair length and AM colonisation were negatively related suggesting that resources are allocated to root hairs rather than to AM fungi in response to P-deficiency. There was evidence that barley and narrowleaf plantain employed different strategies to increase P-acquisition under identical conditions, but root hairs were more effective. This research suggests future barley breeding programmes should focus on maintaining or improving root hair phenotypes and that pursuing enhancements to AM associations under the prevalent agricultural conditions tested here would be ineffectual.

A conceptual model of root hair ideotypes for future agricultural environments: what combination of traits should be targeted to cope with limited P availability?

Phosphorus (P) often limits crop production and is frequently applied as fertilizer; however, supplies of quality rock phosphate for fertilizer production are diminishing. Plants have evolved many mechanisms to increase their P acquisition, and an understanding of these traits could result in improved long-term sustainability of agriculture. This Viewpoint focuses on the potential benefits of root hairs to sustainable production. First the various root-related traits that could be deployed to improve agricultural sustainability are catalogued, and their potential costs and benefits to the plant are discussed. A novel mathematical model describing the effects of length, density and longevity of root hairs on P acquisition is developed, and the relative benefits of these three root-hair traits to plant P nutrition are calculated. Insights from this model are combined with experimental data to assess the relative benefits of a range of root hair ideotypes for sustainability of agriculture. A cost-benefit analysis of root traits suggests that root hairs have the greatest potential for P acquisition relative to their cost of production. The novel modelling of root hair development indicates that the greatest gains in P-uptake efficiency are likely to be made through increased length and longevity of root hairs rather than by increasing their density. Synthesizing this information with that from published experiments we formulate six potential ideotypes to improve crop P acquisition. These combine appropriate root hair phenotypes with architectural, anatomical and biochemical traits, such that more root-hair zones are produced in surface soils, where P resources are found, on roots which are metabolically cheap to construct and maintain, and that release more P-mobilizing exudates. These ideotypes could be used to inform breeding programmes to enhance agricultural sustainability.

South Australian farmers’ markets: tools for enhancing the multifunctionality of Australian agriculture

This paper critically examines the role of farmers’ markets in Australian agriculture. A case study is undertaken in South Australia, where all stallholders at three farmers’ markets situated in Adelaide, Willunga and Berri were surveyed regarding their production and marketing techniques. Overall responses supported literature highlighting the importance of farmers’ markets to the producers who chose to exploit this marketing niche. A strong co-reliance on ‘wholesale sales’ was also recognised, suggesting an important integration of productivist and post-productivist approaches to agricultural development. Of most promise for long-term agricultural sustainability was evidence that certain groups of farmers were found to be realising the potential of these and other alternative markets, in terms of their risk reducing capacity, and diversifying to include various conservation values into their agricultural enterprises. These groups were less concerned about market fluctuations and more concerned with issues of social equity, environmental health and having fun, which meant they unwittingly epitomised the goals of political ecology, by challenging the dominant agricultural methods of production and marketing. It seems these groups also recognised that the direct nature of their transactions would sow beneficial social, environmental and economic ‘seeds’ for change. Finally, it is argued that policies to improve access to farmers’ markets and reduce the cost of participation would assist small scale Australian agricultural producers to evolve smoothly into a multifunctional era.

Effect of organic waste compost and microbial activity on the growth of maize in the utisoils in Port Harcourt, Nigeria

One of the major problems of agricultural soils in the coastal areas of the Niger Delta is the low organic matter content. Therefore, land application of composted organic material as a fertilizer source not only provides essential nutrients to plants, it also improves soil quality and effectively disposes soil wastes. In this study, poultry droppings, spent mushroom wastes, earthworm casts and soil samples were collected from the agriculture farm of the University and composted for 21 days. The composts were applied as nutrient supplements to maize crops at different concentrations of 3000, 9000, 18000 t/ha and control, to determine their effect on crop yield. The patterns of organic waste composting were compared among various combinations. The results obtained showed that organic waste compost application improved soil physical properties, increased nitrogen content, phosphorus, potassium and some micronutrients such as zinc, iron and copper. Vegetative growth parameters were better enhanced in maize stem length, girth, number of leaves and chlorophyll content while other nutrient combinations showed improved yields, especially Soil + spent mushroom wastes (SMW) + poultry droppings (PW) at 40 t/ha. Microorganisms involved in the breakdown of composts were isolated and characterized according to various biochemical reactions. They include Bacillus subtilis , Proteus vulgaris , Pseudomonas , Corynebacterium and Enterobacter species. Therefore, management of organic wastes through composting increases soil organic matter and other nutrients, and therefore had the added benefit of improving soil quality and thereby enhancing long term sustainability of agriculture. Their use also enhances microbial activities which enhances nutrient supply. Keywords: Composts, organic wastes, inorganic fertilizers, microbial activities, soil, maize, nutrient content

Validating the use of 137Cs and 210Pbex measurements to estimate rates of soil loss from cultivated land in southern Italy

Soil erosion represents an important threat to the long-term sustainability of agriculture and forestry in many areas of the world, including southern Italy. Numerous models and prediction procedures have been developed to estimate rates of soil loss and soil redistribution, based on the local topography, hydrometeorology, soil type and land management. However, there remains an important need for empirical measurements to provide a basis for validating and calibrating such models and prediction procedures as well as to support specific investigations and experiments. In this context, erosion plots provide useful information on gross rates of soil loss, but are unable to document the efficiency of the onward transfer of the eroded sediment within a field and towards the stream system, and thus net rates of soil loss from larger areas. The use of environmental radionuclides, particularly caesium-137 (137Cs) and excess lead-210 (210Pbex), as a means of estimating rates of soil erosion and deposition has attracted increasing attention in recent years and the approach has now been recognised as possessing several important advantages. In order to provide further confirmation of the validity of the estimates of longer-term erosion and soil redistribution rates provided by 137Cs and 210Pbex measurements, there is a need for studies aimed explicitly at validating the results obtained. In this context, the authors directed attention to the potential offered by a set of small erosion plots located near Reggio Calabria in southern Italy, for validating estimates of soil loss provided by 137Cs and 210Pbex measurements. A preliminary assessment suggested that, notwithstanding the limitations and constraints involved, a worthwhile investigation aimed at validating the use of 137Cs and 210Pbex measurements to estimate rates of soil loss from cultivated land could be undertaken. The results demonstrate a close consistency between the measured rates of soil loss and the estimates provided by the 137Cs and 210Pbex measurements and can therefore been seen as validating the use of these fallout radionuclides to document soil erosion rates in that environment. Further studies are clearly required to exploit other opportunities for validation in contrasting environments and under different land use conditions.

Small Machines in the Garden: Everyday technology and revolution in the Mekong Delta

AbstractTwentieth-century industrialization in the agricultural landscapes of the Mekong Delta in Vietnam took a very different form from other places, characterized less by a continuous spread of large-scale technology than by its destruction in mid-century and the subsequent spread of small technology which powered scooters, water pumps, and boats. The numbers of these portable motors, an everyday technology in 1960, rose from a few thousand units in 1963 to millions in the present day. The colonial and post-colonial state in Vietnam played a key role in the demise of large technology and, ultimately, of the water infrastructure. Its failures during wartime spurred farmers to adopt cheap, small engines to survive; however, the state's role was complex during this time. Several key factors, including the influence of American aid programmes and the contributions of Taiwanese agricultural advisers, especially those pushing high-yield rice, favoured the adoption of small engines. From an ecological viewpoint, the post-1960 explosion in the use of small motors, especially as water pumps, has brought people and states in Southeast Asia to an ecological impasse as unrestricted use has impacted on water tables, salinity levels, and the long-term sustainability of agriculture in many places. This paper examines the state's indirect role in shaping this silent revolution, and it considers the political and ideological factors underpinning its history.

Sustainable agriculture: A case study of a small Lopez Island farm

Overreliance on fossil fuel based inputs, and transport of inputs and products is seen by many as a threat to long-term agricultural and food system sustainability. Many organic, biodynamic, and low-input farmers limit off-farm inputs, attempting instead to farm within the carrying capacity of their land or local environment. These farmers often accept lower farm productivity because they see reduced reliance on non-renewable inputs as more sustainable. Documentation of low-input agricultural systems through both replicated research trials and case studies is needed in order to better understand perceived and real advantages and tradeoffs. The goal of our study was twofold: (1) to compare liming and biodynamic (BD) preparations in improving pasture on a moderately acidic pasture soil through stimulation of soil microbial activity; (2) to place these findings within the context of a whole farm analysis of economic, plant, and animal health. Treatments included lime, the Pfeiffer Field Spray plus BD compost preparations, and untreated controls. Soil pH, total C and N, microbial activity, forage biomass, and forage quality were evaluated over two growing seasons. Both lime and the Pfeiffer Field Spray and BD preparations were only moderately effective in raising soil pH, with no effect on soil microbial activity or forage yield. Lime significantly reduced forage crude protein but the practical implications of this are questionable given the overall low quality of the forage. While the farm is profitable and economically stable and the animals healthy, the need for future targeted nutrient inputs cannot be ruled out for sustainable long-term production.

Water use patterns of forage cultivars in the North China Plain

Water shortage is the primary limiting factor for crop production and long-term agricultural sustainability of the North China Plain. Forage cultivation emerged recently in this region. A fiver- year field experiment studies were conducted at Yucheng Integrated Experiment Station to quantify the water requirement and water use efficiency of seven forage varieties under climate variability, that is five annuals, i.e., ryegrass (Secale cereale L.), triticale (×Triticosecale Wittmack), sorghum hybrid sudangrass (Sorghum biolor × Sorghum Sudanense c.v.), ensilage corn (Zea mays L.), princes feather (Amaranthus paniculatus L.) and two perennials alfalfa (Medicago sativa L.) and cup plant (Silphium perfoliatum L.). Average ET for five annual varieties ranged from 333 to 371 mm, significantly lower than that of the perennial varieties. ET of alfalfa is 789 mm, which is higher than that of cup plant. Ryegrass and triticale need 1.5 to 2.0 mm water per day, while others 2.9-4.4 mm. Ensilage corn and Sorghum hybrid sudangrass performed better as their irrigation demand is smaller in the dry seasons than others. Ryegrass needs 281 mm irrigation requirement, which is higher than triticale in dry years. Prince's feather is sensitive to climate change and it can be selected when rainfall is greater than 592.9 mm in the growing season. Mean WUE for prince's feather is 20 Kg ha -1 mm -1 , for ensilage corn is 41 Kg ha -1 mm -1 and others is close to 26 Kg ha -1 mm -1 . Our experiments indicate that excessive rain will reduce the production of alfalfae. The results of this experiment have implications for researchers and policy makers with water management strategy of forage cultivars and it also very useful in addressing climate change impact and adaptation issues.