Simulating organic agriculture is a considerable challenge. One reason is that few models are capable of simulating crop-pest interactions and the yield losses they cause. Here, a recently developed ...process-based crop-pest model (Pest-EPIC) was used to simulate conventional and organic agriculture in the European Union for the years 1995–2100. Yields and pesticide application rates were calibrated against FAOSTAT and Eurostat data. Results indicate that current pesticide application rates may be sufficient to control pests and diseases even at the end of the century. The range of simulated yield differences under organic and conventional agriculture under current conditions (e.g., wheat 21–55% (mean 34%) lower yields; potatoes 20–99% (mean 56%) lower yields) closely matched recorded values. Under climate change, the gap between yields under conventional and organic management will remain constant for some crops (e.g., at 3 t/ha for potatoes), but others—susceptible to a larger number of pests and diseases—may experience a widening of the yield gap (e.g., increase of yield difference from 0.8 to 1.6 t/ha for wheat). The presented results-dataset may in future be a valuable resource for integrated assessments of agricultural land use and policy planning, but the inherent uncertainty is still very high.
Rice, wheat, maize, millet, and barley are the five major staple cereal crops in Nepal. However, their yields are low, and imports are needed to meet domestic demand. In this study, we quantify the ...gap between current and potentially attainable yields in Nepal, estimate how much additional fertilizer and irrigation are required to close the gap, and assess if self-sufficiency can thus be achieved. For this, we first test the ability of the crop model EPIC to reproduce reported yields in 1999–2014 accurately. On average, simulated and reported yields at the national level were in the same range, but at the district level, the error was large, as the resolutions of the available climate and soil input data were not high enough to depict the heterogenic conditions in Nepal adequately. In the main study, we show that average yield gaps in Nepal amount to 3.0 t/ha (wheat), 2.7 t/ha (rice), 2.9 t/ha (maize), 0.4 t/ha (barley), and 0.5 t/ha (millet). With additional irrigation and fertilization, yields can be increased by 0.1/2.3 t/ha (wheat), 0.4/1.3 t/ha (rice), 1.6/1.9 t/ha (maize), 0.1/0.3 t/ha (barley), and 0.1/0.4 t/ha (millet), respectively. The results show that providing reliable and affordable access to fertilizer should be a priority for closing yield gaps in Nepal.
Final countdown for biodiversity hotspots Habel, Jan C.; Rasche, Livia; Schneider, Uwe A. ...
Conservation letters,
November/December 2019, 2019-11-00, 20191101, 2019-11-01, Letnik:
12, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Most of Earth's biodiversity is found in 36 biodiversity hotspots, yet less than 10% natural intact vegetation remains. We calculated models projecting the future state of most of these hotspots for ...the year 2050, based on future climatic and agroeconomic pressure. Our models project an increasing demand for agricultural land resulting in the conversion of >50% of remaining natural intact vegetation in about one third of all hotspots, and in 2–6 hotspots resulting from climatic pressure. This confirms that, in the short term, habitat loss is of greater concern than climate change for hotspots and their biodiversity. Hotspots are most severely threatened in tropical Africa and parts of Asia, where demographic pressure and the demand for agricultural land is highest. The speed and magnitude of pristine habitat loss is, according to our models, much greater than previously shown when combining both scenarios on future climatic and agroeconomic pressure.
Brazilian sugarcane production is converting from the traditional manual slash-and-burn to mechanized green cane harvest. The resulting sugarcane trash is mostly left on the field and plowed under at ...the end of a growth cycle, but it could also be recovered and used to increase the energy efficiency of ethanol. In this paper, we explore in a simulation study if straw recovery negatively impacts yields, fertilizer use, nutrient cycling, GHG emissions, and erosion; if there is an optimal recovery rate; and if different recovery rates are advisable for different soil types. We also compare the traditional slash-and-burn management to the green cane management system. Our results show that when performing straw recovery, trade-offs between different factors such as up to 1.3 t/ha lower yields or an up to 30 kg/ha higher demand for fertilizer N under low recovery rates, and higher erosion rates under high recovery rates have to be accepted. Most balanced would be a recovery rate of 40–60%, but the rate should also be adapted to soil type, with less recovery e.g. on soils prone to erosion, and to economic considerations. A comparison between green cane harvest without straw recovery and the traditional slash-and-burn method shows lower erosion rates and higher soil organic carbon contents, but also a higher fertilizer consumption due to nitrogen immobilization on areas under green cane management. Due to these trade-offs, one method cannot be unequivocally commended over the other.
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Rising air temperatures are the main reason for the expected reduction in land suitability for coffee cultivation under climate change in Central America. One of the reasons farmers ...use shade trees is to create a cooler microclimate in coffee plantations located in warming areas; therefore, adjusting the shade levels could alleviate future high temperatures. Even though data on expected climatic changes are available, no studies have addressed the cooling potential of shading in coffee production systems. In this study, we use regional climate information (RCP 4.5) and a simple shade model to explore the potential of shading as an adaptation practice in the coffee areas in Central America. A model was developed to estimate the required shade levels for Coffea arabica L. based on mean air temperature. Modeled and observed shade data were compared. Results indicate that compared to 2000, an overall increment of 23 ± 18% of shading would be required to alleviate the warming conditions by 2050. The shading will be more beneficial to coffee areas at medium and high altitudes than to areas at low ones. Also, the number of coffee areas that require dense shade levels (shading > 60%) may double by 2050. This would lead to a boost in tree biomass (carbon content) but also increase the competition for the coffee plants and consequently affect coffee yields. Trade-offs between adaptation, mitigation, and productivity objectives are expected in the coffee areas in the future.
Cowpeas (Vigna uniculata L. Walp) are grown by many smallholder farmers in sub-Saharan Africa for food and their ability to fix nitrogen even under stress. Their performance depends on the indigenous ...rhizobial strains that live in symbiotic association with the roots; it can be enhanced if the seeds are inoculated with more effective ones. Data of the effectiveness of the technique under a variety of climatic conditions is rare. Here, we thus use a model to upscale two field experiments conducted in Namibia to include different climate change scenarios. The simulations show that non-inoculated cowpeas have mean yields of 0.5 t/ha and inoculated cowpeas 1 t/ha. If climatic conditions are favorable (cool and wet), estimated yield differences increase to over 1 t/ha. In dry years (< 200 mm), the average yield difference is only 0.1 t/ha. In the far future (2080-2100), instances of dry and hot years will increase. Using inoculated cowpea seeds instead of non-inoculated ones thus does not benefit farmers as much then as in the near future (2030-2050). In conclusion, using cowpea seeds inoculated with an efficient rhizobial strain can significantly increase yields under varying climatic conditions, but yield advantages decrease markedly in very dry and hot years.
Climate mitigation targets must involve the agricultural sector, which contributes 10%–14% of global anthropogenic greenhouse gas (GHG) emissions. To evaluate options for implementing mitigation ...measures in the agricultural sector, farmers’ knowledge, positions, and attitudes towards agricultural GHG emissions, their accounting, and reduction need to be understood. Using an online survey, we asked 254 German farmers about their motivation to reduce GHG emissions and their acceptance of possible regulation schemes. We examined differences between relevant farming sectors, i.e., conventional versus organic and livestock keeping versus crop-cultivating farms. Results show that German farmers are aware of climatic changes and feel a general commitment to reducing GHG emissions but lack sufficient information. We identified agricultural magazines as the most effective tool for disseminating relevant knowledge. German farmers would feel motivated to adopt climate-friendly farming styles if products were labeled accordingly and if they received subsidies and public acknowledgment for their effort. As long as there is no regulation of agricultural GHGs through taxes or subsidies, personal motivation is yet the strongest motivation for voluntary emission reduction. Our findings are timely for the further development of strategies and instruments that reduce agricultural GHG emission and account for the farmers’ views. The dataset is available for further investigations.
Organic agriculture is an attractive land use alternative to conventional farming in terms of environmental and biodiversity protection. The official German target is a 30% share of organic ...agricultural area by 2030, while German stakeholders consider 24% realistic and 44% desirable. It is unclear how such a shift may affect the food and land use system. We use data from a crop/pest model to estimate yield differences between conventional and organic systems, and the FABLE accounting tool to assess changes in indicators like calories available per person and day, and the extent of cropland, pasture and area where natural processes predominate. We investigate how an increase in organic agricultural area may affect these indicators up to 2050, and if adaptation measures may become necessary to ameliorate the potential pressure to expand cropland or raise import rates. The results show that if organic agricultural area is increased, there will be a calorie deficit of 7–80 kcal per person and day, corresponding to 1000–5000 km
2
of missing cropland. The deficit will disappear without any changes to the system by 2045 at the latest due to demographic and technological development. No additional cropland at all would be required if crop productivity increased at a higher rate than observed today, and an additional 600,000 ha could be freed even with a 30% share of organic agriculture. A higher share of organic agriculture is thus a realistic target for Germany, but technological advancements should accompany the transformation to minimize cropland demand.
Economic impacts of pesticide regulations are assessed using five alternative methodologies. The regulations include crop supply-enhancing eradication programs and crop supply-decreasing pesticide ...bans. Alternative assessment methodologies differ regarding assumptions about market price and crop acreage adjustments. Results show that market and producer adjustments substantially impact conclusions about winners and losers from regulations, and estimated welfare effects can differ widely between the different methodologies. For small technological changes such as the hypothetical pendimethalin regulation, farm budgeting and sector modeling yield similar estimates. For more severe technological changes—like the boll weevil eradication program—simple budgeting approaches lead to a substantial bias.
This study estimates the risks of agricultural pesticides on non-target organisms and the environment by combining detailed pesticide application data for 2015 with the Danish risk indicator ...Pesticide Load. We quantify and map the pesticide load of 59 pesticides on 28 crops and pastures in the EU. Furthermore, we investigate how recent bans on 14 pesticides in the EU could reduce pesticide use and load. Key findings show that the highest pesticide loads per hectare occur in Cyprus and the Netherlands due to high application rates and a high proportion of vegetable production. Chlorpyrifos caused the highest pesticide load per hectare on more than half of the assessed crops before its ban. The ban of 14 pesticides between 2018 and 2023 potentially reduced pesticide loads by 94%, but unobserved substitution effects could offset pesticide load reductions. Although bans on active substances are justified to control certain endpoint risks, our results highlight the potential weaknesses of bans that merely shift risks. These findings contribute to the ongoing scientific and societal discourse on efficiently mitigating pesticides' impacts on non-target organisms and the environment. However, to improve the evaluation of pesticide use, it is vital to enhance the reporting on detailed pesticide use for individual crop-pesticide combinations.
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•Quantified pesticide-related risks in the EU with the Pesticide Load•The cultivation of vegetables incurs the highest pesticide load per hectare•Ban of pesticides decreased pesticide load substantially•The substitution of banned pesticides could offset reduction of pesticide load
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