Determining an effective approach to replacing chemical fertilizer with organic fertilizer is a difficult challenge for the Chinese government. This paper constructs a dynamic analysis framework with broader application than previous statistical and case studies by theoretically deriving the impact of farmers' participation in contract farming on their organic fertilizer application behavior. The framework analyzes farmers' intertemporal organic fertilizer application behavior under the two scenarios of participation and nonparticipation in contract farming. Participation in contract farming positively impacts organic fertilizer application behavior in both the short and long terms. Survey data from 473 vegetable farmers in Shandong province of China were used to conduct an empirical analysis, and the endogenous switching probit model was used to solve the endogeneity problem of farmers' participation in contract farming. The empirical analysis supports the above results: farmers' participation in contract farming increases their probability of applying organic fertilizer by 50.7%. Robustness tests conducted using the recursive bivariate probit model and replacing the dependent variable (the intensity with which farmers replace chemical fertilizer with organic fertilizer) confirm the research results. Further heterogeneity analysis shows that farmers' participation in contract farming has a more obvious promoting effect on organic fertilizer application behavior in the older group, the group with an education level of primary school or below and the small-scale farming group. Therefore, the government should promote participation in contract farming, especially among elderly, low-education and small-scale farmers, to improve the adoption level of organic fertilizer in China.

This paper examined organic fertilizer adoption and its effects on two household food security indicators and gender-based farm labor use among smallholder farmers in Northern Ghana. An endogenous switching regression analysis shows that observed and unobserved farmer background factors determine farmers’ decision to adopt organic fertilizer as well as the outcomes from adoption. On average, adoption is associated with an 11% increase in per capita food consumption and a 55% reduction in household food gap duration. Adoption is also related to an increased labor use by 5.9 (90%) of female worker days and 1.3 (9%) of male worker days per acre, placing nearly all (82%) of the increased labor burden on female farmhands. We recommend mitigation of factors that hinder farmers from adopting the input and provision of female-user-friendly labor-saving devices for organic fertilizer use tasks.

An understanding of the nexus of organic fertilizer use decisions that smallholder farmers take is essential to designing relevant policy to support adoption in sub-Saharan Africa. In this paper, we applied exploratory factor analysis (EFA) on observed farmer decisions to identify a set of common management approaches that farmers in the northeastern part of Ghana adopt in using organic fertilizer. After identification, seemingly unrelated regression (SUR) analysis was applied to relate each approach to farmer characteristics that influence uptake decisions. The EFA identified four approaches, labeled as Augmentary Compost Use Approach, Urban Human Waste Organic Fertilizer Approach, Integrated Livestock Manure Approach and Mineral Fertilizer Cost Constraint Organic Approach. Each of the first three approaches involves a set of strategic farmer decisions which could be supported to increase organic fertilizer use. The SUR analysis showed that the uptake of each approach is affected by different subsets of farmer characteristics. However, participation in organic fertilizer management training positively influences the adoption of all four approaches. Thus, we recommend free training of smallholder farmers as a core element of any policy package to support organic fertilizer adoption.

Two solid state anaerobic digesters (SSADs), 15 L each, were set up for co-digestion of switchgrass with primary digestate of a liquid anaerobic digester (LAD) and the recirculating leachate. Both the LAD and two SSADs were operated at 50°C. The results showed that the bioreactors were not started up stably until day 16 and day 47 for reactors A and B, respectively. The supplement of LAD digestate or injection of sodium hydroxide (NaOH) into the recirculating leachate readily reinitiated the biogas production to normal daily high rates of the two individual SSADs, one on day 16 and the other on day 47. In contrast to reactor A, there was a longer lag phase for bioreactor B, however, it showed 46.2% [77.9 vs 53.3 L kg−1 volatile solid (VS)] more cumulative biogas yields, and higher reduction rate of total solid, VS, cellulose and hemicellulose of 29.5, 31, 40.6 and 15%, respectively, which was likely due to optimized pH and NaOH pretreated switchgrass during start-up period. Methane contents of biogas increased gradually and stabilized at 50% for both reactors, indicating a normal operation of anaerobic digestion lasted for at least 100 days. The determined parameters of digested residues met China organic fertilizer standard (NY 525-2012) except for high moisture and low total nutrient contents. Therefore, the product of SSAD has the potential value of organic fertilizer. It is concluded that the LAD digestate can be reused as inoculums by co-digestion with agricultural residues for biogas and organic fertilizer production in SSAD.

Agriculture in the Altiplano and Andean Mountains is experiencing threats to sustainability mainly due to intensive cultivation of quinoa driven by international markets. This recent export-oriented production system is causing the degradation of soils and reducing productivity, therefore, agro-technological innovations are necessary to sustain cropping systems while maintaining organic quality (mostly quinoa). In this work, we searched for native Trichoderma species associated with plants from the Andean highlands to obtain an environmentally friendly and organic alternative to chemical fertilizers. We obtained different Trichoderma isolates from quinoa, potato and maize roots and soil, which were identified as Trichoderma harzianum, as well as other species. Twelve of the isolates were cultured in pairs to stimulate the production and secretion of compounds of diverse chemical nature that we called collectively ‘secondary metabolites’ (SMs). Crude extracts of SMs were used to inoculate selected crops to determine their plant growth promoting potential compared with two commercially available controls, chemical fertilizer and a bio-fertilizer. Results showed that SMs significantly promoted lettuce and radish growth and increased quinoa grain yield. Indole acetic acid was detected in all SM extracts that promoted plant growth, suggesting that this plant regulator might be responsible for the plant growth promoting activity. In conclusion, the Trichoderma-derived SMs approach appears to be a promising, simple and accessible technology for small-scale farmers in order to insure the sustainability, affordability and accessibility of food production in the Andes.

Sophisticated capital intensive waste-recycling technologies are unviable in small rural abattoirs in India due to low volume of wastes (principally blood and rumen digesta) generated and lack of infrastructural facilities. We report recycling of slaughterhouse wastes as an organic fertilizer, ‘bovine-blood-rumen-digesta-mixture’ (BBRDM). Bovine blood and rumen digesta were mixed in 3:1 ratio in a metallic container, boiled and stirred continuously till the mixture was largely free of water. The mass was sun-dried for 3 days to obtain the final product. BBRDM was applied for field cultivation of tomato (Lycopersicon esculentum L., local variety ‘Patharkuchi’) in West Bengal state (India) during 2012–13 and 2013–14. We compared tomato yields obtained with BBRDM (N:P2O5:K2O 30.36:1:5.75) and conventional inorganic fertilizers [diammonium phosphate (DAP), N:P2O5:K2O 18:46:0 + potash, N:P2O5:K2O 0:0:44]. BBRDM was applied at a higher rate compared with DAP + potash to meet the farmers’ desire for enhanced yields. 75 kg ha−1 was applied at the 2nd week while 150 kg ha−1 was applied at the 8th week after transplantation. Yields (total fruit weight) obtained from BBRDM-treated plants were higher in comparison with DAP + potash-fertilized plants by 46–48% as the former supplied 2.5 times more nitrogen (N) than the latter. The partial factor productivity of DAP + potash was 73–76% higher than BBRDM. Conversely, as BBRDM was produced through local entrepreneurship from slaughterhouse wastes, the cost of this organic product would be expected to be much lower than the commercial inorganic fertilizer. Furthermore, application of BBRDM negates the environmental cost of treating slaughterhouse effluent. Considering the same cost of applying 225 kg fertilizer ha−1, higher yield with BBRDM should result in greater potential revenue for the farmer compared with yields with DAP + potash. The C/N ratio of BBRDM is 4.8, having relatively high N content. Accordingly, rapid release of plant-available N was observed in BBRDM-fertilized soils. The temporal increase in soil NH4+may be attributed to lack of soil N immobilization. Local farmers are willing to accept the new fertilizer as a substitute for currently used chemical fertilizers.

Stocker performance and production from mixed cool- and warm-season perennial pastures are important determinants of agricultural sustainability that can be influenced by management. We evaluated the factorial combination of three sources of nutrient application (inorganic only, organic+inorganic combination, and organic only) and two forage utilization regimes [low grazing pressure (LGP) and high grazing pressure (HGP)] on steer stocking density and rate, performance and production during 7 years of pasture management {tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] overseeded into existing Coastal bermudagrass [Cynodon dactylon (L.) Pers.] sod} on a Typic Kanhapludult in Georgia, USA. Nutrient source had few major impacts on responses, except for lower animal performance with organic fertilization (broiler litter) than with organic+inorganic and inorganic only fertilization, especially with LGP. Seasonal changes in stocking weight and rate occurred, not only as expected due to environmental conditions and dominant forage species present, but that also counteracted expected differences imposed by grazing pressure; signaling negative feedback of HGP on forage productivity. Steer performance was greatest in spring and summer under both grazing pressures, but was significantly reduced with increasing grazing pressure in the autumn and winter due to low forage availability. Across years, steer gainha−1 (863kgha−1) was not different between grazing pressures, but gainha−1 declined with time under HGP and was stable with time under LGP. Reducing grazing pressure to a moderate level can lead to equivalent steer production as HGP, and would likely contribute to a more sustainable balance among production, socio-economic and environmental goals. These multi-year results will help cattle producers in warm, moist climates design and implement more sustainable grazing systems.

Rice is the most important agricultural commodity of the Lao People's Democratic Republic (Lao PDR), produced largely using traditional methods with limited inputs of fertilizers and other chemicals. The country has a wide diversity in rice production systems and rice varieties, with over 3000 different varieties recorded. The rich diversity and the production environment and methods are favorable for organic rice production. Investigations were carried out to describe soil fertility conditions, management practices, opportunities and problems associated with organic production methods for rice. Soils used for rice production are mostly of low fertility, with low organic matter and N-availability. In spite of this, virtually no fertilizer inputs are used for upland rice production. Inorganic fertilizer inputs for lowland rice production have increased rapidly over the past decade, but are still below 20 kg ha−1. The most important nutrient sources are rice straw and manure from buffalo and cattle. Chromolaena odorata plays an important role in nutrient cycling in upland rice systems and is sometimes added to lowland fields. In a range of fertility management studies, yield increase ranged from 2 to 89% for manure, straw or rice husk applied at modest rates (3 t ha−1), 32–156% for modest rates of inorganic fertilizer (60 kg N ha−1) and 36–167% for combined application of manure or crop residues with inorganic fertilizer. The response to locally produced commercial organic fertilizer was poor. The most promising inputs and strategies available to optimize yields in organic rice production systems are (1) optimizing use of locally available nutrients, mostly from manure, crop residues and weed biomass, (2) N addition through green manure and legumes growing in rotation and (3) additions of P through guano or rock-phosphate. The Lao PDR is fortunate to have substantial bat guano deposits in limestone caves. Extensive experience is available on straw and husk management for lowland systems and green manure species for upland production systems.

Organic farming seems to be a solution in environmentally sensitive zones such as the protection zone of Tahtalı Dam, which supplies fresh water to Izmir, the third largest city in Turkey. Greenhouse vegetable production is the major agricultural activity in this area (Menderes Township). However, due to the pollution risk from agriculture, governmental authorities have issued a regulation discouraging the use of chemicals within the collection basin of the dam. An on-farm project was conducted in 2001 to introduce organic greenhouse vegetable production in the Tahtalı Dam preservation area and to serve as a model for other areas in Turkey facing similar ecological problems. Two irrigation levels and four organic fertilizers were tested on the growth of cucumbers (Cucumis sativus cv. Sardes). The four fertilizers were two rates of farmyard and poultry manure (30 and 50 tons ha−1) with and without two organic fertilizers based on either bacteria or algae. During the growing period, pests and diseases were monitored weekly and preparations allowed in organic agriculture were used when necessary. Plant diseases did not create any significant problem, but the pest population, in particular spidermites, increased. No significant differences in cucumber yield were found between the fertilizer and irrigation treatments tested. However, it should be noted that yields from the addition of 30 tons ha−1 of farmyard or poultry manure and organic fertilizers were the same as those for 50 tons ha−1 of manure alone. The average total yield was 13 kg m−2, within an acceptable range for short-term crop production in this region, but 55% lower than a conventional substrate culture trial nearby. However, due to reduced production costs and a price premium for organic products, the organic produce yielded a net return of US$1.12–1.79 per m2 whereas that for conventional bag culture produce was US$0.55 per m2. Our results indicate that, under present conditions, organic greenhouse cucumber production has less environmental impact and is more economic than conventional bag culture, due to reduced chemical input and reduced operating and initial investment costs.

A case study in eastern Virginia provides evidence that both environmental and farm profit goals may be satisfied by alternative nitrogen (N) management strategies for grain production. We used a linear programming framework with an N mass balance model to calculate returns from several options for providing N to crops. Replacing single applications of inorganic N fertilizer with split applications or with additions of organic N were found to reduce the potential for N loss from cropland and to increase net returns. For some N management strategiesy however, adoption may require financial and educational assistance. As a result, water quality policies may benefit by including such incentives.

Several factors can directly or indirectly affect the nutritional quality of crops. Among these are soil factors, such as pH, available nutrients, texture, organic matter content and soil-water relationships; weather and climatic factors, including temperature, rainfall and light intensity; the crop and cultivar; postharvest handling and storage; and fertilizer applications and cultural practices. This paper deals primarily with fertilizer and cultural management practices, and on certain environmental factors that affect the nutritional quality of field crops and of fruits and vegetables. Earlier research that has investigated the nutritional status of crops grown with either chemical fertilizers or organic fertilizers is discussed. These studies often have given contradictory results on crop yields and on crops' mineral and vitamin contents. Other factors, such as maturity at harvest, postharvest handling and storage, anti-nutritive components, and residues of chemical fertilizers and pesticides are reviewed with respect to food safety and quality, and their implications for human and animal health. Future research needs are identified so that comparable results and valid comparisons can be obtained to identify the best management practices to ensure that food is safe and nutritious for the consumer.