Traditional Crop Rotation Research Articles

Productivity of crop rotations with different types of fallow and their effect on the humus content in sod-podzolic soil the Middle Urals

The research was carried out in the conditions of the Perm Region on sod-podzolic heavy loamy soils in a long stationary plot trial, laid down in 1977. The purpose of the research is to study the effect of various types of fallow on crop rotation productivity and humus content in the soil. The data are given for two rotations (2009–2022) of fallow-grain–grass crop rotations with various types of fallow – with manurial, sown with clover, sown with melilot, sideral with clover and sideral with melilot – without mineral fertilizers and with fertilizers (N60P30K60). It was found that in the sown fallows, the mass of root and mowing plant residues of meadow clover and yellow melilot, depending on the nutrition background, reaches 4.08–4.36 t/ha with a nitrogen content of 41.8–46.9 kg/ha, phosphorus 16.7–18.6 kg/ha and potassium 42.7–69.6 kg/ha. In sideral fallow with clover and clover biomass, 6.99–9.04 t/ha and 6.83–8.53 t/ha of dry matter with a content of 133.5–148.1 kg/ha of nitrogen, 34.3–41.2 phosphorus and 121.2–148.9 potassium were supplied to the soil, respectively. The application of organic fertilizers in the fallow field contributed to an increase in the humus content by 0.19 abs.% to the initial (2.04 %) in the variant without mineral fertilizers and by 0.69 abs.% in the variant with the introduction of mineral fertilizers to the initial (2.08 %) Clover sideral fallow also contributed to an increase in the humus content in the soil by – 0.38–0.52 abs.%. There was an increased productivity of crop rotation with sideral melilot fallow (2.22–2.25 t/ha of grain units per year) relative to the traditional crop rotation with pure fallow (2.08–2.11 t/ha of grain units per year). Cultivation of crops in all studied crop rotations was energetically efficient, the energy efficiency coefficient was 3.63...4.48 in the variants without mineral fertilizers, against the background of NRK – 2.38...3.21.

Evaluating the incentive for soil organic carbon sequestration from carinata production in the Southeast United States

Soil organic carbon (SOC) can be increased by cultivating bioenergy crops to produce low-carbon fuels, improving soil quality and agricultural productivity. This study evaluates the incentives for farmers to sequester SOC by adopting a bioenergy crop, carinata. Two agricultural management scenarios – business as usual (BaU) and a climate-smart (no-till) practice – were simulated using an agent-based modeling approach to account for farmers’ carinata adoption rates within their context of traditional crop rotations, the associated profitability, influences of neighboring farmers, as well as their individual attitudes. Using the state of Georgia, US, as a case study, the results show that farmers allocated 1056 × 103 acres (23.8%; 2.47 acres is equivalent to 1 ha) of farmlands by 2050 at a contract price of $6.5 per bushel of carinata seeds and with an incentive of $50 Mg−1CO2e SOC sequestered under the BaU scenario. In contrast, at the same contract price and SOC incentive rate, farmers allocated 1152 × 103 acres (25.9%) of land under the no-till scenario, while the SOC sequestration was 483.83 × 103 Mg CO2e, which is nearly four times the amount under the BaU scenario. Thus, this study demonstrated combinations of seed prices and SOC incentives that encourage farmers to adopt carinata with climate-smart practices to attain higher SOC sequestration benefits.

SOYBEAN CULTIVATION IN CROP ROTATIONS OF THE TRANS-URALS REGION

Data on the influence of weather conditions, varieties, predecessors, soil cultivation, and mineral nutrition on soybean yield compared with spring wheat are presented. The research was conducted in short-term (two years) and stationary field experiments (eight years) on leached chernozem soils in the central natural zone of the Kurgan region. In the ecological trial, Siberian (SibNIISK-315, Sibiryachka) and European (Bilyavka) selection soybean varieties were tested in favourable hydrotechnical conditions in 2019, with good soil moisture (predecessor fallow), providing productivity potential at the level of 2.00 – 2.23 t/ ha. With a similar cultivation technology and unfavourable natural factors in 2020, a slight yield advantage was observed for the SibNIISK-315 variety (1.77 t/ha compared to 1.60 t/ha for Sibiryachka and 1.72 t/ha for Bilyavka). The Sibiryachka soybean variety stood out for its grain protein content (35.4%). The yield and grain quality data of these varieties can be considered promising for the conditions of the Trans-Urals region. Cultivating the SibNIISK-315 soybean variety as a second crop after fallow in arid years (ETC 0.3 – 0.6) allowed for successful drought resistance, with soybeans yielding at 1 t/ha. Spring wheat in these years yielded no more than 0.68 t/ha. Under sufficient moisture conditions (ETC 1.0–1.2), soybean yield for ploughing was 1.42–1.78 t/ha, and surface treatment was 1.33–1.66 t/ha. A positive effect on outcome was noted with small doses of nitrogen fertilisers – 10 and 20 kg of active substance per hectare of crop rotation area. With relatively equal yields, surface treatment is a less costly option. Traditional crop rotation (fallow – three years – wheat) and crop rotation with soybeans (fallow – wheat – soybeans – wheat) during the years of research (2015 – 2022) showed similar productivity. Still, higher grain production profitability was achieved in the crop rotation with soybeans: 58.1% compared to 35.8%.

Ascertaining land allocation decisions of farmers about the adoption of carinata as a potential crop for sustainable aviation fuel production in the Southern United States

AbstractThe adoption of a bioenergy crop is affected by various factors, including but not limited to the characteristics of farmers, farm economics, market forces, and physical environment. This study develops a spatially explicit agent‐based model for ascertaining the adoption rate of carinata (Brassica carinata) among the farmers in the Little River Experimental Watershed located in the southern state of Georgia in the United States. Each farmer's adoption behavior is modeled using the profitability difference between traditional crop rotations (with and without carinata at different contract prices), the adoption rate of neighboring farmers, and their land allocation decisions from managing a risky portfolio of enterprises. Carinata production in the winter season once every 3 years has no conflict with the most profitable and popular traditional row crop rotations, such as cotton‐cotton‐cotton and cotton‐cotton‐peanut, to a larger extent. The results show that 28% and 85% of farmers in the watershed will adopt carinata after 33 years at a contract price of $13/bushel (bu) under two different assumptions of low (2.5%) and high (5%) initial neighborhood adoption rates. The proportions of land allocated to carinata to the total farmland under field crops are 38% and 85% after 33 years under the same low and high neighborhood adoption rates, respectively. Our results suggest that fixing the appropriate contract price of carinata will bring additional profits to farmers without any significant foreseeable agronomic risks, thereby increasing the adoption rate of carinata at a regional level.

Agro-economic substantiation of the feasibility of green manured fallow in sugar beet crop rotations of the Central Chernozem Region

The aim of the study is to find out the feasibility of including green manured fallow in specialized sugar beet crop rotations by comparing necessary assessment indicators with their values in a traditional crop rotation with black fallow against the background of unequal fertilization levels. The study was based on the analysis of experimental data from a long-term stationary experiment, laid out simultaneously in all fields and variants on typical chernozem in triplicate. The results are as follows: within the same fertilization levels, no significant differences in the yield of winter wheat (sugar beet precursor) were revealed, and the yield of sugar beet in a crop rotation with green manured fallow was stably higher (no more than 5 to 7%), an increase in yield relative to the control fertilizer variant (6 tons of manure per hectare per year) against the background of a double rate of manure in combination with mineral fertilizers amounted to 21.7 to 23.4% for wheat and 14.3 to 15.6% for beets with an increase in the productivity of crop rotations (in natural and value terms) by 1.2 times, but an increase in costs by 1.3 times caused an absolute decrease in the level of profitability by 23 to 25%. Differences in the assessment indicators for specific fertilization variants increased over time due to an unequal degree of soil fertility reproduction, and therefore in the fifth cycle of the crop rotation with black fallow turned out to be 1.1 to 1.3 times greater than in the green manured rotation.

Yield and economic performance of crop rotation systems in South Dakota

AbstractCrop yield and economic profitability, both highly dependent on local crop management, soil characteristics, and weather conditions, are among the most influential factors to consider when considering a cropping system. The objective of this study was to compare the economic returns of three different 4‐yr diverse crop rotations with that of a 2‐yr traditional crop rotation in eastern South Dakota. The rotations included were (a) corn (Zea mays L.)–soybean [Glycine max (L.) Merr.]–spring wheat (Triticum aestivum L.)–pea (Pisum sativum L.) (CSSwP), (b) corn–pea–winter wheat–soybean (CPWwS), (c) corn–oat (Avena sativa L.)–winter wheat–soybean (COWwS), and (d) corn–soybean (CS). Results showed that total cost for the CS rotation was 7.2, 14.9, and 18.2% greater than the COWwS, CSSwP, and CPWwS rotations, respectively. Whereas CS rotation had comparable corn yield with CSSwP and COWwS rotations, its soybean yield ranked the lowest among all the rotations. When N fertilizer application fell below the level necessary to achieve for yield maximization, the CS rotation demonstrated a lack of resilience as indicated by a continual decline in economic returns over time. In comparison, the CSSwP rotation demonstrated high resilience to reduced N fertilizer application rate, and its net revenue was the highest among all rotations and surpassed the CS. Our results suggest that extending the traditional CS rotation to the more diversified CSSwP rotation could simultaneously reduce input costs and overreliance on N fertilizer.

Dynamics of change in broomrape populations (Orobanche cumana Wallr.) in Romania and Russia (Black Sea area)

Abstract The emergence of new broomrape populations (races) has been observed in the past 20 years in several countries (Romania, Moldova, Ukraine, Russia, Turkey, Bulgaria, Spain, Serbia, and China) where sunflower is frequently grown in the same sites without applying traditional crop rotations. Differential lines for sunflower broomrape races A to F have been secured. The new broomrape races have been identified by researchers as races G and H. The question of whether the same broomrape mutations can occur in one year and affect the same countries remains unsolved. Several results of new broоmrape population emergences in some of the affected will be presented in the paper. A total of 390 genotypes were studied at four Romanian localities (Cuza Voda, Crucea-Stupina, Braila-Valea Canepii, and Tulcea-Agighiol) in 2014. At all four localities, a certain degree of sunflower broomrape infestation was observed in control hybrids and lines (Performer, LC-1093, LG-5661, and PR64LE20), which indicated the emergence of new populations higher than race H. The 390 studied genotypes had different reactions in all four localities. In 2015, 10 hybrids and controls were studied at five Romanian localities (Ciresu-Braila, Iazu-Ialomita, Stupina-Constanta, Topolog-Tulcea, and Viziru-Braila) and, according to the results, only hybrid Hy-7 was resistant in all localities. The results obtained from the three studied localities showed the emergence of new sunflower broomrape populations not controlled by gene for race H. Self-fertilization of hybrid Hy-7 produced the F2 generation in 2016. In 2017, broomrape resistance was studied at the infested (contaminated) plot at the All-Russian Research Institute of Oil Crops by the name of Pustovoit V.S. – VNIIMK in Rostov on Don. The plot was found to be infested by new broomrape populations originating from Russia, Ukraine, Romania, Turkey, and Spain. The obtained results showed an infestation degree in 17.1% plants of hybrid Hy-7, 35% in the F2 generation of Hy-7, control hybrids PR64LE25, LG-5580 and Donskoy-22 showed 19.4, 23, and 100% broomrape infestation, respectively. In conclusion, the plot contained broomrape populations which cannot be controlled by race H gene. According to the obtained results, a permanent change in variability of broomrape populations can be confirmed practically year after year. At present, new broomrape populations found at several localities are locally dispersed. Geneticists and breeders have to make joint efforts in further detailed studies of broomrape variability.

Depth-dependent soil organic carbon dynamics of croplands across the Chengdu Plain of China from the 1980s to the 2010s.

Agricultural soils have tremendous potential to sequester soil organic carbon (SOC) and mitigate global climate change. However, agricultural land use has a profound impact on SOC dynamics, and few studies have explored how agricultural land use combined with soil conditions affect SOC changes throughout the soil profile. Based on a paired soil resampling campaign in the 1980s and 2010s, this study investigated the SOC changes of the soil profile caused by agricultural land use and the correlations with parent material and topography across the Chengdu Plain of China. The results showed that the SOC content increased by 3.78gC/kg in the topsoil (0-20cm), but decreased in the 20-40cm and 40-60cm soil layers by 0.90 and 1.26gC/kg respectively. SOC increases in topsoil were observed for all types of agricultural land. Afforestation on former agricultural land also caused SOC decreases in the 20-60cm soil layers, while SOC decreases only occurred in the 40-60cm soil layer for agricultural land using a traditional crop rotation (i.e. traditional rice-wheat/rapeseed rotation) and with rice-vegetable rotations converted from the traditional rotations. For each agricultural land use, SOC decreases in deep soils only occurred in high relief areas and in soils formed from Q4 (Quaternary Holocene) grey-brown alluvium and Q4 grey alluvium that had a relatively low soil bulk density and clay content. The results indicated that SOC change caused by agricultural land use was depth dependent and that the effects of agricultural land use on soil profile SOC dynamics varied with soil characteristics and topography. Subsoil SOC decreases were more likely to occur in high relief areas and in soils with low soil bulk density and low clay content.

Manejo y diversidad de las comunidades arvenses en las estepas cerealistas: propuestas para una gestión sostenible

Alarcon Villora, R., Sanchez, A.M., Hernandez-Plaza, E. 2019. Management and diversity of weed communities in Mediterranean cereal steplands: new proposals under the sustainability paradigm. Ecosistemas 28(3):36-45. Doi.: 10.7818/ECOS.1821 The word weed is used to define the herbaceous plants that inhabit the cultivated fields. In rainfed crops, weeds have been considered one of the main causes of yield loss. However, works on the relationship between management practices, crop yields and weed communities in cereal steplands, are still scarce. Nonetheless, some of these works challenge the prevailing negative view on weeds, while questioning the efficacy of a weed management solely based on herbicide use. In Spain, the large extension of cereal steplands (6.5Mha) made the management of its weed diversity a question of great relevance. In this study, we summarize the state of the art on the effects of management practices on weed communities of cereal steplands. We identify knowledge gaps, and point out new research to support the development of management strategies based on the recovery of traditional crop rotations, the reduction of soil tillage and the use of organic fertilization. These will serve as the basis for the design of management strategies that permit to maintain crop yields and biodiversity.

Conservation agriculture based sustainable intensification: Increasing yields and water productivity for smallholders of the Eastern Gangetic Plains

In the Eastern Gangetic Plains (EGP) region of South Asia cropping systems are predominantly rice-based and comprise rice and non-rice crops (e.g. maize, wheat, lentil, mungbean, jute) in rotation. There are large gaps between potential crop yields and those achieved in farmers’ fields, primarily due to poor crop and soil management practices. Increasing climate variability and injudicious use of natural resources, particularly water and soil, mean that cropping systems have little resilience and are showing signs of being unsustainable. We hypothesized that replacing traditional crop rotations, grown under conventional tillage (CT) and with full residue removal, with crops grown under zero tillage (ZT) and with partial or full residue retention would improve both crop and cropping system yields, and reduce crop water demand, thus increasing the water productivity of cropping systems across the EGP. We evaluated four tillage-and-crop-establishment scenarios in three major cropping systems (rice-wheat, RW; rice-maize, RM; rice-lentil, RL) across eight districts of the EGP in 433 farmers’ fields between 2015 and 2017. We compared farmers’ traditional crop establishment practices (T1) against three scenarios based on the principles of conservation agriculture based sustainable intensification (CASI) and comprising a “partial CASI” option (T2: only non-rice crops grown under CASI management) and two “full CASI” options in which both crops were grown under CASI management; in T3 rice was direct seeded rice (DSR) and in T4 rice was transplanted without prior land preparation such as puddling (UPTR).Rice yields under all systems were not significantly different between CT (PTR) and CASI (ZTDSR and UTPR) but there was a significant yield gain of around 5% in both full and partial CASI on the yield of wheat and maize in the RW and RM systems. There were significant spatial trends in rice yields across all cropping systems. Total in-crop water (irrigation plus rainfall) usage was similar for the rainfed PTR, DSR and UTPR in all cropping systems as rice was primarily a rainfed crop grown during the wet season, however CASI practices reduced the required irrigation water, and thus the total in-crop water, to the dry season wheat or maize (but not to lentil) crops, compared to CT. This resulted in increased irrigation water productivity (greater than 27%) and total water productivity (greater than 26%) in both the wheat and maize crops. In the RW and RM systems irrigation water productivity was increased by over 25% and total water productivity by around 10%. These results indicate that the uptake of full or partial CASI practices, particularly in RM and RW systems, can lead to improvements in both cropping system and water productivity for smallholder farmers in the EGP.

Development of a process-based simulation model of camelina seed and oil production: A case study in Northern Italy

Camelina (Camelina sativa L. Crantz) is an oilseed crop gaining interest due to its potential portfolio of derived bio-based products. The inclusion of camelina in traditional crop rotations is fostered by the possibility of growing it either as spring or autumn crop, the latter being of particular interest in the Mediterranean region. Here we present a process-based simulation model for camelina, CAMEL, and we evaluate its performances in predicting yield, oil production and principal fatty acid accumulation. CAMEL integrates a crop simulator with a model of soil water balance and with models to reproduce main seed qualitative traits. It was calibrated and validated using ten camelina field experiments performed in Northern Italy in non-limiting conditions for soil water availability and nitrogen fertilization during 2015–2017. The results for phenology (average error of 6.7 days), and biomass and yield accumulation (RRMSE = 23% for aboveground biomass and 9% for yield) denoted the ability of CAMEL to reproduce field observations of crop development and growth across growing seasons and sowing periods. The large correlation between simulated and measured oil fractions highlights the correct reproduction of the main camelina fatty acids. This work lays the basis for the use of CAMEL as a support tool to assess seed yield and quality in Northern Italy, besides further work is still needed to add the impact of management practices on yield and qualitative traits, before adopting CAMEL for in-season farmer support.

Enhanced nitrogen imbalances in agroecosystems driven by changing cropping systems in a coastal area of eastern China: from field to watershed scale.

Agricultural activities exacerbate nitrogen (N) imbalances in the agroecosystem by disturbing the N inputs and outputs, yet the influence of changes in cropping systems on the N balance of agroecosystems remains unclear. In this study, at the field scale, we calculated the N balance of four cropping systems, (1) traditional crops with traditional crop rotation (G-G), (2) vegetables with traditional crop rotation (V-G), (3) vegetables with vegetable rotation (V-V), and (4) greenhouse vegetables (GHV); then analyzed the influence of changes in cropping systems from 1995 to 2015 on the N balances in the agroecosystems in sub-watersheds of the Dagu River. The results indicate that N balances were higher in GHV, V-V, and V-G than G-G, due to significantly higher inputs of N fertilizers and lower N use efficiency (NUE) in vegetable cultivation compared to traditional crops. Driven by economic benefits between 1995 and 2015, V-G, V-V, and GHV replaced G-G in a considerable number of cultivation areas in the sub-watersheds. These changes resulted in an increase of 109.9-170.1% in the N balance in the agroecosystem in the sub-watersheds between 1995 and 2015. In the entire watershed, the total N surplus contribution by V-V, V-G, and GHV increased from 39.3% to 79.1% between 1995 and 2015. These findings suggest that increased vegetable cultivation contributed to the increased risk of N pollution in agricultural production. Thus, there should be a focus on the management of cropping systems to control N loss from agricultural lands.

Extensive usage of insecticide and changing crop rotation patterns: A South Dakota case study.

Driven by factors such as an increased reliance on genetically modified crops, government policies, and market forces, the crop mix in South Dakota and elsewhere in the United States has become less diverse and moved toward the production of corn and soybeans as the most predominant cash crops over the past two decades. Coinciding with a reduced complexity of crop rotation practices, the prevalence of mono-cropping has increased and crop chemical usage has changed as well. Overall, the reduced reliance on traditional crop rotation practices for mitigating pests corresponds with an increase in crop acres treated with insecticides, expressed as a proportion of total cropland acres, and referred to in the literature as the extensive usage of insecticides. In this paper, we identify how changing cropping patterns in South Dakota have affected the extensive usage of insecticides, an aspect often overlooked by producers and policy makers. Results indicate that increased corn production has contributed to an increase in the share of cropland acres treated with insecticides at the county level in eastern South Dakota.

Mitigating Groundwater Depletion in North China Plain with Cropping System that Alternate Deep and Shallow Rooted Crops.

In the North China Plain, groundwater tables have been dropping at unsustainable rates of 1 m per year due to irrigation of a double cropping system of winter wheat and summer maize. To reverse the trend, we examined whether alternative crop rotations could save water. Moisture contents were measured weekly at 20 cm intervals in the top 180 cm of soil as part of a 12-year field experiment with four crop rotations: sweet potato→ cotton→ sweet potato→ winter wheat-summer maize (SpCSpWS, 4-year cycle); peanuts → winter wheat-summer maize (PWS, 2-year cycle); ryegrass–cotton→ peanuts→ winter wheat-summer maize (RCPWS, 3-year cycle); and winter wheat-summer maize (WS, each year). We found that, compared to WS, the SpCSpWS annual evapotranspiration was 28% lower, PWS was 19% lower and RCPWS was 14% lower. The yield per unit of water evaporated improved for wheat within any alternative rotation compared to WS, increasing up to 19%. Average soil moisture contents at the sowing date of wheat in the SpCSpWS, PWS, and RCPWS rotations were 7, 4, and 10% higher than WS, respectively. The advantage of alternative rotations was that a deep rooted crop of winter wheat reaching down to 180 cm followed shallow rooted crops (sweet potato and peanut drawing soil moisture from 0 to 120 cm). They benefited from the sequencing and vertical complementarity of soil moisture extraction. Thus, replacing the traditional crop rotation with cropping system that involves rotating with annual shallow rooted crops is promising for reducing groundwater depletion in the North China Plain.

Economics, energy, and environmental assessment of diversified crop rotations in sub-Himalayas of India.

Reducing the carbon footprint and increasing energy use efficiency of crop rotations are the two most important sustainability issues of the modern agriculture. Present study was undertaken to assess economics, energy, and environmental parameters of common diversified crop rotations (maize-tomato, and maize-toria-wheat) vis-a-vis traditional crop rotations like maize-wheat, maize + ginger and rice-wheat of the north-western Himalayan region of India. Results revealed that maize-tomato and maize + ginger crop rotations being on par with each other produced significantly higher system productivity in terms of maize equivalent yield (30.2-36.2 t/ha) than other crop rotations (5.04-7.68 t/ha). But interestingly in terms of energy efficiencies, traditional maize-wheat system (energy efficiency 7.9, human energy profitability of 177.8 and energy profitability of 6.9 MJ/ha) was significantly superior over other systems. Maize + ginger rotation showed greater competitive advantage over other rotations because of less consumption of non-renewable energy resources. Similarly, maize-tomato rotation had ability of the production process to exploit natural resources due to 14-38% less use of commercial or purchased energy sources over other crop rotations. Vegetable-based crop rotations (maize + ginger and maize-tomato) maintained significantly the least carbon footprint (0.008 and 0.019 kg CO2 eq./kg grain, respectively) and the highest profitability (154,322 and 274,161 Rs./ha net return, respectively) over other crop rotations. As the greatest inputs of energy and carbon across the five crop rotations were nitrogen fertilizer (15-29% and 17-28%, respectively), diesel (14-24% and 8-19%, respectively) and irrigation (10-27% and 11-44%, respectively), therefore, alternative sources like organic farming, conservation agriculture practices, soil and water conservation measures, rain water harvesting etc. should be encouraged to reduce dependency of direct energy and external carbon inputs particularly in sub-Himalayas of India.

An evaluation of the life cycle cost of rapeseed oil as a straight vegetable oil fuel to replace petroleum diesel in agriculture

The use of straight vegetable oil (SVO) as biofuel has been recognized as a valid substitute of diesel fuel in the agricultural sector under specific circumstances. Its direct use reduces most of the chemical processes involved when converting it into biodiesel, thus lowering harmful emissions. This study presents the economic analysis of a self-supply farming model that uses rapeseed as its fuel base. This model addresses agricultural environmental concerns and can even minimize dependence on the fluctuating costs of diesel fuel. The use of SVO in agriculture can help reduce farmers’ vulnerability to fossil fuel prices. The economic evaluation of the model proposed in this study shows clear economic benefits of introducing rapeseed to the traditional crop rotation of wheat and barley. The key factors analyzed in this model are diesel fuel price, diesel fuel grants and crop aids. The current situation in Spain favors the use of diesel fuel in agriculture rather than rapeseed SVO due to an 8% profit difference. However, results show that changes in key factors slightly affect the profit margin, calculating a difference of only 3.7% for particular factor combinations. Combined environmental-friendly agriculture supporting policies are necessary to cover this slight profit difference to promote this biofuel. ► We economically evaluate small-scale rapeseed oil self-supply used as biofuel. ► We model six different crop systems scenarios, two using rapeseed oil as biofuel. ► The introduction of rapeseed in the traditional crop rotation is economically advantageous. ► Scenarios using diesel fuel show slightly higher economic benefit results. ► We show that this difference can be minimized applying environmental policy measures.

Net changes of main ions in the soil profile of irrigated field plots in central Spain

Implementation of improved irrigation schedules in some semiarid zones improve water efficiency and can be recommended where occasional periods of heavy rainfall may remove some of the accumulated salts. We hypothesized, however, that the leaching pattern of the main ions may differ regarding their potential contribution to the total salt discharge. The experiment was conducted near Madrid in Spain on a typical Xerofluvent soil with sandy-loam texture in the first 0.5 m. For 4 years, a traditional crop rotation of corn–wheat–corn–oat (Zea mays L.–Triticum aestivum L.–Zea mays L.–Avena sativa L.) was planted and two irrigation treatments (traditional and improved) were applied only to the corn. In an experimental set-up of 24 plots, samples of the soil solutions were extracted 61 times during the experiment at soil depths of 0.4, 0.9 and 1.4 m. During the experiment, drainage volume was estimated in plots under the two irrigation schedules. Main ions in the soil solution were SO42−, Cl−, Ca2+, Na+ and HCO3−. These solutes accounted for 88% of total salt discharge under the two irrigation treatments. Two main patterns of salt leaching were observed. For most main ions, except HCO3−, the input to discharge ratio was lower than one. Also for HCO3− , the irrigation treatment did not affect the leaching pattern (higher input than discharge under the two irrigation treatments). Improved irrigation schedules can be implemented without increasing the total salt load, but attention should be paid to specific leaching patterns of individual ions.

Large‐scale patterns of summer and winter bird distribution in relation to farmland type in England and Wales

Over the last 30 yr, the loss of traditional crop rotations and the polarisation of pastoral and arable farming have led to a marked reduction in mixed agriculture in Britain at both the individual farm and the landscape scale. We assess the potential impact of this change on lowland farmland birds by examining the extent to which distributions (as shown by national atlases of summer and winter birds) of different species are associated with arable, pastoral or mixed‐farming landscape types. Relatively few species appeared as either widespread generalists, equally associated across the three broad farmland types, or specialists associated only with one landscape type. Most were associated with two farmland types but distributions showed seasonal differences. During the breeding season there was an approximate ratio of 2:2:1 of species associated with arable, mixed and pastoral landscapes. However, in winter, most species were at highest abundance in mixed farming landscapes. This coincided with a reduction in the number of species associated with pastoral landscapes relative to the breeding season, whereas the number of species associated with arable landscapes remained relatively stable. These patterns are likely to be related to foraging requirements; granivorous birds tended to be associated with arable habitats, which tend to be more seed‐rich, and invertebrate‐feeding species tended to be associated with mixed or pastoral ones, which may be more invertebrate‐rich. The relative importance of mixed landscapes in winter was attributed to seasonal changes in the distribution of some invertebrate feeders, particularly small insectivores (pipits, chats and wagtails), and some of those species considered to be widespread in summer. The results have two important implications for future research. First, most research on farmland birds has, to date, focused on species associated with arable farming during the breeding season. More research is required on species associated with agricultural grasslands, reflecting its importance for farmland birds in Britain, and on the winter ecology of farmland birds in general. These results also emphasise the importance of mixed habitats for farmland birds, particularly in winter, and suggest that further changes in agricultural practices causing reduction in habitat diversity will be detrimental for the farmland bird community. However, widespread benefits may be derived from small scale measures that increase habitat diversity within farmland, for example field margin management options within agri‐environment schemes and support for traditional farming practices in some Environmentally Sensitive Areas.

Reconsideration of Traditional Crop Rotation of Paddy and Others in Nara Basin.

Reconsideration of Traditional Crop Rotation of Paddy and Others in Nara Basin.

Traditional farming and key foraging habitats for chough Pyrrhocorax pyrrhocorax conservation in a Spanish pseudosteppe landscape

1. Agricultural land devoted to low‐intensity practices supports many declining bird species in Europe. The potential effects of intensification or abandonment of traditional farming practices are assessed from the point of view of the conservation of the chough Pyrrhocorax pyrrhocorax. 2. The study was conducted in Los Monegros (north‐east Spain), in a pseudosteppe landscape of special relevance for this species. In this area traditional farming survives in the form of low‐intensity arable systems including fallowing and extensive sheep grazing. 3. Foraging choughs showed a strong selection for field margins, avoided any remnant of the original scrubland and halophitic vegetation, and utilized other habitats maintained by traditional crop rotation (e. g. fallow, stubble) at different times of the year. 4. A highly complex pattern of habitat selection was found which was not only related to seasonal changes in habitat availability, but also differed between territorial pairs and the non‐breeding population. This emphasizes the importance of taking all the different components of bird populations into account when analysing interactions between habitat selection and the annual farming cycle. 5. Chough habitat selection suggests that both agricultural intensification and land abandonment would have detrimental consequences for this species in Los Monegros. The maintenance of traditional farming is recommended, especially by promoting the use of long fallow rotations grazed extensively by livestock, encouraging the increase of grassland edges around landholdings and sand roads, and maintaining a low input of biocides. These management measurements could also favour most other endangered species of steppe birds, and could be supported by the establishment of Zonal Programmes under the CAP Agri‐Environment Regulation (2078/92).