Cereal-legume Rotation Research Articles

Detecting and Explaining Long-Term Trends in a Weed Community in a Biennial Cereal–Legume Rotation

The technique of Dynamic Factor Analysis (DFA), which aims to reduce the dimensionality of time-series data, was utilized in order to model the changes over time in eight different long-time-series weeds (26 years) growing in a biennial cereal–legume rotation. The aim of the present study was to determine the existence of long-term trends in a weed community and to identify the factors that determine them. A common trend was extracted that captured the main signal of abundance over time, indicating latent influences affecting all species. Canonical correlation analysis showed strong associations between the common trend and specific weed species, suggesting differential responses to this latent factor. Local (temperature and precipitation) and global weather factors (North Atlantic Oscillation (NAO)) were considered as explanatory variables to explain the common trend. The local weather variables considered did not play a significant role in explaining the commonly observed trend. Conversely, NAO showed a significant relationship with the weed community, indicating its potential role in shaping long-term weed dynamics. DFA was found to be useful for studying the variability in multivariate weed time-series without the need for detailed a priori information on the underlying mechanisms governing weed population dynamics. Overall, this study provided valuable insights into the long-term drivers of weed dynamics and set the stage for future research in this area.

Early-stage soil organic carbon stabilization in conservation agriculture-based cereal systems

In South Asia, the sustainability of conventional tillage and input-intensive cereal-based cropping systems (such as rice-rice and rice-wheat) is under scrutiny due to soil organic carbon depletion, stagnant productivity, and adverse environmental impacts stemming from greenhouse gas emissions (N2O, CH4, and CO2). Against this backdrop, a long-term field experiment was initiated in 2009 at three sites in India (Karnal, Patna, and Aduthurai) and one site in Bangladesh (Gazipur) to assess four scenarios (S) reflecting current and future diversified crop rotations and conservation agriculture (CA) practices: S1 - double cereal rotation with conventional practices; S2 - double cereal plus legume rotation with partial CA; S3 - double cereal plus legume rotation with full CA; and S4 - futuristic diversified cereal-legume rotations with full CA. This study delved into the dynamics and stabilization of soil organic carbon across all scenarios and sites. Replicated soil samples were collected from depths of 0–15 cm and 15–30 cm after two crop cycles. We analyzed Walkley-Black carbon (WBC), total organic carbon (TOC), and various carbon pools with different oxidizability, determining the amount of carbon stabilized under CA-based scenarios and identifying optimal systems for carbon economy in South Asia. On average, active and passive carbon pools, TOC, and WBC stocks followed the order: S4 > S3 > S2 > S1 at all sites, except Gazipur, where the order was S3 > S4 > S2 > S1. CA practices stabilized applied carbon inputs to soil organic carbon at an annual rate of 1.7 %, with greater stabilization observed under S4 (11.7 %) > S3 (10.6 %) > S2 (7.8 %), regardless of location. Rice-rice sites exhibited a higher carbon stabilization rate (13.4 %) compared to rice-wheat sites (6.7 %). A significant proportion of stabilized carbon (63 %) was allocated to passive pools in soils under S2, S3, and S4, highlighting CA's potential to enhance carbon stability. Using a linear indexing technique, we identified that both S3 and S4 are conducive to better carbon stabilization, yield sustainability, and environmental co-benefits. Consequently, full CA systems with best management practices (S3) and best management practices with crop diversification (S4) are recommended for sustainable crop production in the major double cereal growing regions of South Asia, including India and Bangladesh.

Crop Rotation and Diversification in China: Enhancing Sustainable Agriculture and Resilience

Crop rotation and diversification (CRD) are crucial strategies in sustainable agriculture, offering multiple benefits to both farmers and the environment. By alternating crops or introducing diverse plant species, CRD practices improve soil fertility, reduce pest populations, and enhance nutrient availability. For example, legume-based rotations increase soil nitrogen levels through biological nitrogen fixation, reducing the need for synthetic fertilizers. Moreover, these practices promote more efficient water and nutrient use, reducing the reliance on synthetic fertilizers and minimizing the risk of pests and diseases. This review synthesizes findings from recent research on the role of CRD in enhancing sustainable agriculture and resilience, highlighting the potential contributions of these practices towards climate change mitigation and adaptation. Specific crop rotation systems, such as the cereal–legume rotation in temperate regions and the intercropping of maize with beans in tropical environments, are reviewed to provide a comprehensive understanding of their applicability in different agroecological contexts. The review also addresses the challenges related to implementing CRD practices, such as market demand and knowledge transfer, and suggests potential solutions to encourage broader adoption. Lastly, the potential environmental benefits, including carbon sequestration and reduced greenhouse gas emissions, are discussed, highlighting the role of CRD in building resilient agricultural systems. Collectively, this review paper emphasizes the importance of CRD methods as sustainable agricultural practices and provides key insights for researchers and farmers to effectively integrate these practices into farming systems.

Fertilizer application and chemical fertility of a lixisol in a crop rotation system in the southern Sudanian zone of Burkina Faso

The lack of organic matter in soils and the high cost of mineral fertilizers are constraints to the intensification of agricultural production in Burkina Faso. The aim of this study is to evaluate the effects of the joint application of organic and mineral matter on soil fertility under crop rotation conditions. The study was carried out at the research station in Farakoba, from 2018 to 2020. The system was a 4x4 split-plot factorial with 3 replications. The 4 treatments corresponded to 4 crop rotations used as the main factor and 4 manures as the secondary factor. We used 4 rotation sequences: Sorghum-Fonio, Soya-Fonio, Mung bean-fonio, Sorghum-Mung bean. The four secondary treatments corresponded to four fertilizers: control with no fertilizer application; NPK and urea; Compost+poultry manure; Compost+poultry manure+Burkina phosphate). Results showed that legume-cereal rotations resulted in a 2.3% drop in C/N ratio, while the total exchangeable base (TEB) and the cation exchange capacity (CEC) increased by 82.53% and 24.08% respectively compared to the soil at the start of cultivation. Compared to the soil at the beginning of the crop, the soya-fonio rotation resulted in CEC and TEB increases of 26.87% and 86.55% respectively. The Compost+poultry manure treatment recorded significantly higher TEB and CEC contents, followed by the Compost+poultry manure+Burkina Phosphate and Compost+NPK+Urea treatments. Compared to the Compost+NPK+Urea treatment, the Compost+Poultry manure +Burkina Phosphate treatment resulted in TEB and CEC increases of 18.7% and 5.06% respectively. The results showed a negative and non-significant correlation between C/N and the parameters Ca, Na, Mg, TEB, CEC and saturation level. On the other hand, the correlation between C/N and K was positive and non-significant (r=0.036). In a context of high mineral fertilizer costs, fertilization techniques and productivity of systems can therefore be improved by combining local fertilizing resources such as poultry manure, Burkina phosphate and legume rotations.

Quantifying and Disentangling the Competition Effect of a Weed Community in a Long-Term Biennial Cereal-Legume Rotation

Weeds are a permanent constraint on crop productivity in agriculture. Due to the importance of the effect of weeds on the crop, there has been great interest in establishing the competitive ability of each species to optimize its control. This work presents a new methodology approach to determining the relative competitiveness of weed species based on population dynamics theory, which is applied to establish the competitiveness of Papaver rhoeas L. (PAP), Veronica hederifolia L. (VER), Descurainia sophia L. (DES) and Fumaria spp. (FUM) infesting a biennial cereal-legume rotation under conventional tillage. Data to fit the nonlinear population dynamic models were obtained from a long-term experiment (32 years) in Mediterranean drylands. The results showed asymmetric competitive interactions, and the competitive ability of weeds was crop specific. In cereals, the competitiveness ranking order was FUM > PAP > VER > DES, with strong interspecific competition; in legumes, it was VER > FUM > DES > PAP, with weak interspecific competition intensity. Overall, intraspecific competition was stronger than interspecific competition in the rotation system. The information gained in these studies can provide insights into the role of the intraspecific and interspecific competition in weed communities and help identify weed species that are relatively poor competitors in given crops.

Diversity of soil fertility management options in maize-based farming systems in northern Benin: A quantitative survey

Introduction: Maize-based production systems in Sub-Saharan Africa are largely based on family farming, which is characterized by low-input, nutrient-mining agriculture and practices. These systems usually promote soil degradation through loss of organic matter and erosion. The present study characterizes farms and main soil fertility management options in maize-based farming systems of the northern Benin.Methods: The study was conducted in the municipalities of Malanville, Banikoara and Bembèrèkè. We sampled randomly and interviewed 262 maize farmers, and the statistical analysis (distribution of means and frequencies, chi-square, ANOVA, etc.) was performed.Results and discussion: The results show that maize farming characteristics and socioeconomic conditions (land use and labor, production activities and land allocation, institutional arrangements on land, access to labor and capital, etc.) were diverse across locations and exhibited a wide variation within locations. Several practices were used for the management and sustainable maintenance of soil fertility in maize production systems in northern Benin: maize-legume intercropping, cotton-maize rotation, and mineral and organic fertilizers application. Most of farmers occasionally or regularly used mineral fertilizers (95.4%), followed by legume-cereal rotation/ intercropping (51.9%). Overall, 23.6% and 58.4% of farmers consistently used mineral fertilizer over the last 5 and 10 years, respectively. The amount of applied mineral fertilizer did not significantly vary between locations with an average (applied day after sowing, DAS) of 131.7 ± 13.7 (22 ± 8 DAS), 58.7 ± 9.6 (44 ± 5 DAS) and 164.7 ± 25.4 (38 ± 11 DAS) kg ha−1 for NPK, urea and Mix NPK + urea, respectively applied at, and days after sowing. Most farmers spread the fertilizer around the plants without covering with soil particles. Manure was applied exclusively to food crops through transporting and corralling (28.2%); and most farmers also used manure from their own livestock while few farmers used cattle corralling. Farmyard manure was mainly spread (100% of respondents) on the surface before plowing at the beginning of the rainy season. Maize farmers applied mineral fertilizer based on the level of initial soil fertility (naturally fertile or poor, degree of erosion etc.) and fertilizer purchase costs. Manure was not widely used as an alternative to chemical fertilizers; therefore, farmers need more strengthening and technical assistance on the production of organic fertilizers and manure storage. The findings are useful for policymakers on encouraging the successful implementation of sustainable soil fertility management strategies of maize-based farming systems in northern Benin.

Long-term tillage, residue management and crop rotation impacts on N2O and CH4 emissions from two contrasting soils in sub-humid Zimbabwe

The respective contribution of conservation agriculture (CA) principles (no-tillage, permanent soil cover/mulch and crop rotations) on greenhouse gas (GHG) emissions is still unclear. This study was conducted at two long-term experimental sites established in 2013 in Zimbabwe, on an abruptic Lixisol at Domboshava Training Center (DTC) and on a xanthic Ferralsol at the University of Zimbabwe Farm (UZF). The purpose of the study was to unravel the individual and combined effects of tillage, mulching and rotation on N2O and CH4 emissions in low nitrogen (N) input maize-based cropping systems (< 60 kg N ha−1) and to compare emissions within maize rows and between maize rows. We hypothesised that integrating no tillage, mulch and cereal-legume rotation would enhance N2O emissions. Six treatments, replicated four times were investigated: conventional tillage, conventional tillage with rotation, no-tillage, no-tillage with mulch, no-tillage with rotation, no-tillage with mulch and rotation. The main crop was maize (Zea mays L.) and treatments with rotation included cowpea (Vigna unguiculate L. Walp.). Gas samples were regularly collected using the static chamber method in the maize row and inter-row spaces during the 2019/20 and 2020/21 cropping seasons and during the 2020/21 dry season. Soil moisture and mineral N were measured in the 0–20 cm soil depth. In 2019/20, cumulative total N2O emissions were significantly higher in mulch treatments at DTC, while at UZF N2O emissions were higher with cowpea rotation. Cumulative total N2O emissions ranged from 215 to 496 g N2O-N ha−1 yr−1 and from 226 to 395 g N2O-N ha−1 yr−1, at DTC and UZF, respectively. In 2020/21, N2O emissions were much lower and no differences were found between treatments on both sites (145 to 179 g N2O-N ha−1 yr−1 and 83 to 136 g N2O-N ha−1 yr−1 at DTC and UZF, respectively). A significant relationship was found between soil nitrate and daily N2O emissions. At UZF, highest N2O emissions were observed at a water-filled pore space of 60–70%. There were no significant differences in yield-scaled N2O emissions between treatments at both sites for the two seasons. DTC was a net source of CH4 (694 g CH4-C ha−1 yr−1 on average), while UZF was a net sink of CH4 (−494 g CH4-C ha−1 yr−1 on average). No evidence was found for in situ CH4 production at DTC, and an external source is most likely. Our study indicates that for low N input cropping systems in the sub-humid tropics, N loss through N2O is low.

Legumes can increase the yield of subsequent wheat with or without grain harvesting compared to Gramineae crops: A meta-analysis

Legumecereal crop rotation is considered a sustainable intensive rotation model that can reduce nitrogen (N) inputs, improve soil quality, increase biodiversity and reduce environmental pollution risks. However, compared with Gramineaecereal rotations, quantitative assessment of the effects of legumecereal rotations on grain yield and N use of subsequent cereal crops are lacking. There is also no comprehensive analysis of factors explaining the change in yield effects of subsequent cereal crops, or the differences in these effects, depending on whether the grains of the legume crops are harvested. Here, a meta-analysis of the effects of legumewheat (LW) and Gramineaewheat (GW) rotations on wheat yield and N use was conducted based on 453 observations from 62 studies published worldwide. Our results suggested that compared with GW rotations, LW rotations had a positive effect on wheat yields. Wheat yield was significantly increased by 21.28 % and 31.71 % (P < 0.05) under legume-harvested grainwheat (LHGW) rotation and legume that non-harvested grainwheat (LNHGW) rotation systems, respectively. The positive benefits of legume crops on wheat yield were reduced to some extent by their harvest. The main factors affecting wheat yield were fertilization rates and climate and soil types, with weight ratios of 0.32, 0.21 and 0.16, respectively. For fertilization rates, wheat yield benefits decreased with increases in N fertilizer inputs, and we identified significant positive benefits in temperate, subtropical and Mediterranean climates (P < 0.05). For soil types, sandy and loamy sand soils with low clay contents generally had the best wheat yield benefits. Furthermore, compared with GW rotations, LW rotations increased N use efficiency by 8.57 % on average, which was significantly affected by N inputs (P < 0.05). Therefore, the introduction of legume crops into the GW rotation system can increase wheat yields and reduce N applications regardless of whether legume grains are harvested. Moreover, legume crops have the best wheat yield benefits under low N input conditions, which can make an important contribution to the sustainable intensification of global wheat production.

Residual Effect of Finely-Ground Biochar Inoculated with Bio-Fertilization Impact on Productivity in a Lentil–Maize Cropping System

Biochar fertilization improves soil fertility and carbon sequestration, implying agricultural and environmental advantages. The effect of different sized previously applied biochar and biofertilizer agents on succeeding crops remains poorly known for legume–cereal cropping cycles. This study compared different particle-sized biochar and biofertilizer strains applied to lentils for their residual impact on subsequent maize growth, nutrition, and soil fertility without further polluting the environment. Three particle sizes (&lt;2, 2–5, 5–10 mm) of Babul tree (Acacia arabica) wood biochar was obtained through grinding and sieving and applied prior to the lentil (first) crop at a rate of 500 g m−2. The commercial Rhizobium leguminosarum products Biozote-N and Rhizogold were inoculated to lentil seeds before sowing. The effect of biochar and biofertilizer agents on the succeeding maize (second) crops was evaluated for soil and crop performance. Findings revealed that particle sizes of &lt;2 mm biochar and Biozote-N inoculation enhanced plant height, leaf area and leaf area index, biological yield, and thousand grain weight of the subsequent maize crop. Maize grain yield was enhanced by 2.5%, tissue N uptake by 15%, nitrogen uptake efficiency by 17%, grain protein content by 15%, extractable P by 17%, and soil bulk density by 3% with a residual biochar particle size of &lt;2 mm and Biozote-N inoculation. It was concluded that the finely grounded (&lt;2 mm) biochar particle combined with inoculation of Biozote-N was superior to larger particle sizes for enhancing crop growth and improving soil fertility status at the residual level, benefiting the subsequent crop in a legume–cereal rotation system.

Conservation agriculture improves agronomic, economic, and soil fertility indicators for a clay soil in a rainfed Mediterranean climate in Morocco

CONTEXTDeclining rainfall with increasing variability, increasing temperature extremes, and declining soil fertility are threatening crop production and ultimately food security in the rainfed Mediterranean environment in Morocco. Conservation agriculture (CA) practices such as reduced tillage, soil cover, and appropriate crop rotation are recognized as a set of adaptive agricultural systems in such climate-sensitive regions. Systematic evaluation of agronomic, economic, and soil fertility indicators with medium-and long-term adoption of CA in different crop rotations in such variable climatic conditions is needed to drive wider adoption of CA in the region. OBJECTIVEThe objective of this study was to systematically evaluate agronomic, economic, and soil fertility indicators under CA and conventional tillage (CT) using field experimentation (medium-term) and simulation modeling (long-term) for a clay soil of a rainfed Mediterranean environment. METHODSMethodologies included the following: 1) Field experimentation for 5 years (2015–2019), comparing CA and CT in four major food crops: wheat, barley, lentil, and chickpea, conducted in Merchouch, Morocco. The objective was to determine the effect of CA on crop productivity, yield stability, profitability, precipitation use efficiency, and soil fertility indicators of individual crops and cropping systems. (2) Dynamic simulation modeling to understand the long-term effect of adopting CA and CT under cereal–legume and cereal–cereal rotation systems. Using 5 years of experimental data, we calibrated and validated a Decision Support System for Agrotechnology Transfer (DSSAT) model for four crops; and ran the model for 36 years for two major rotations. RESULTS AND CONCLUSIONSAcross the five contrasting rainfall years, in comparison to CT, CA had greater yield stability and increased wheat grain yield by 43%, barley by 8%, lentil by 11%, and chickpea by 19%. In 5 years of cereal-legume rotation cycle, CA resulted in increased system yield (by 20%), total benefits (by 40%), precipitation use efficiency (by 13%), and available soil moisture (by14%) with production cost reduced by 14.5%. The CA system had higher soil organic matter (+7%), available phosphorus (+3%), and exchangeable potassium (+15%) than in CT, although all differences were non-significant. Our field experiment and long-term simulation results suggest that CA adoption improves a range of agronomic and economic, and soil fertility indicators compared to CT in the clay soil of a rainfed Mediterranean environment. SIGNIFICANCEThe outcomes of this experimental and simulation study on the multiple benefits of CA provide evidence for extensionists, policymakers, and farmers to drive its wider adoption in Morocco and similar production environments.

Soil nitrogen status can be improved through no-tillage adoption particularly in the surface soil layer: A global meta-analysis

United Nations ‘Sustainable Nitrogen Management’ (UNEP/EA.4/L.16) resolution calls for adopting best practices for recovery and recycling of N. Bulk of the soil N stock is in soil organic matter (SOM) form. The stabilization of SOM following conversion to no-till practice will, therefore, regulate N flux and storage in soils. To realize the no-tillage (NT) effect on soil N, a global meta-analysis was conducted with 2,268 pairs of data points from 327 peer-reviewed articles. Increases of 21 and 16% in total N concentration and N stock, respectively, were noted under NT compared to conventional tillage (CT) in the surface soil layer (0–10 cm). However, no such changes were accounted for down the profile. Continental and temperate climates recorded significant gains in total N in NT while the effect was negligible in tropical and dry climates. Soil N increased in NT irrespective of soil texture; coarser the texture, marginally higher was the gain. An incremental rise in soil N was evident with an increase in the duration of NT adoption. The cereal-cereal and cereal-legume rotations had marginal advantages with NT over other cropping systems. The surface 0–10 cm layer recorded the largest N stock under NT, which remained similar down the depth. A decrease in soil pH was noted with conversion to NT practice, but soil electrical conductivity was comparable with CT. No-tillage favoured the soil N and as a consequence, fertilizer-N use under no-till condition, must take into account of the potential N release from SOM for achieving higher N-use efficiency.

Effect of long-term cropping systems on soil hydrophobicity of a clay loam soil under dryland conditions in southern Alberta

The objective was to quantify the effect of crop rotations, crop type, life cycle, nitrogen fertilizer, manure application, and fallow on soil hydrophobicity (SH). The SH was measured for a long-term (16 yr) dryland field experiment on a Dark Brown clay loam soil in southern Alberta, Canada. Mean SH was significantly (P ≤ 0.05) greater in rotations with grass, perennial crops, manure application, and continuous cropping; whereas cereal–legume rotations and N fertilizer effects were undetectable. A strong, positive correlation occurred between SH and soil organic carbon concentration (r = 0.73). Soil water repellency should be measured on these plots using water-based methods.

Irrigated crop rotation and phosphorus fertilizer-manure addition impacts on soil water repellency of a clay loam soil in southern Alberta

Soil water repellency (SWR) was measured for a 28 yr field study under irrigation on a clay loam Dark Brown soil in southern Alberta. The objectives were to study the effect of legume–cereal crop rotations, feedlot manure, and phosphorus (P) fertilizer application on soil hydrophobicity (SH) and soil water repellency index (RI) under irrigation. Mean SH and RI were similar (P &gt; 0.05) for a legume–cereal and cereal rotation and were unaffected by P fertilization. However, P fertilization shifted the RI classification from slight to subcritical. In contrast, SH was significantly greater for manured than nonmanured treatments, while RI was unaffected. Soil organic carbon (SOC) concentration was significantly (P ≤ 0.05) correlated with SH (r = 0.74), but not with RI (r = −0.17). This suggested a closer association between the quantity of SOC and quantity of hydrophobic compounds (SH method) compared with the hydrophobic coatings inhibiting infiltration of water (RI method). No significant correlation between SH and RI (r = −0.09) suggests that SH is not a good predictor of SWR using the RI method. Overall, manure application increased SH and P fertilization shifted the RI classification from slight to subcritical. In contrast, legume–cereal rotations had no influence on SH and SWR using RI method compared with continuous cereal.

Stakeholder Perceptions on Multiple Ecosystem Services of Soil Conservation Practices in Tiwa Watershed, Northwest Ethiopia

Understanding stakeholders’ perceptions and preferences regarding different soil conservation practices (SCPs) are essential for addressing short-term ecosystem service (ES) values from a particular field. Demand for multiple ESs of SCPs has received limited attention. This study aimed to examine stakeholders’ perceptions on multiple ESs of SCPs in Tiwa watershed, Northwest highlands of Ethiopia. Results of the multi-criteria analysis method indicated that the combination of vegetation stabilised terracing, compost and crop residue under the legume-cereal crop rotation (LCCR) system was the most preferred conservation method for enhanced provisional, regulating and social ESs. Soil bunds stabilised with Sesbania sesban shrubs were the second preferred by providing more ESs. Subsequently, the inclusion of crop residue into the soil under the LCCR system, followed by compost use was perceived to regulate soil fertility and increase crop yields, and reduce the cost of chemical fertiliser in the short term. Hence, it is recommended that a combination of terraces stabilised with Sesbania sesban, and compost under the LCCR system can be the best alternative approach for multiple ESs in the highland of Ethiopia.

Drivers of diazotroph community structure and co-occurrence in a Northern Great Plains pulse crop rotation system

The Northern Great Plains of the United States and Canada have seen an increase in pulse crops like pea, lentil, and chickpea acreage in dryland and irrigated systems. Rotating pulse crops into cereal crop production systems could reduce the demand for nitrogen fertilizer due to the symbiotic relationship with nitrogen fixing bacteria called diazotrophs. Legume-diazotroph relationships are well studied, but little is known about the free-living bacteria of the bulk soil in the legume-cereal rotation systems. Here we determine the community structure of the overall (16S) and diazotroph (nifH) soil microbiome in pulse-cereal rotations across the state of Montana. Many variables influenced the microbial community structure, but and among them, irrigation caused a significant shift in the composition of the communities and co-occurrence network topology. Interestingly, the diazotrophic communities in dryland soil are more robust and contain more generalist compared to irrigated soils. Co-occurrence networks support the identification of different diazotrophic keystone taxa such as Firmicutes in irrigated and Proteobacteria in dryland soils. Linking farm management practices and crop productivity with microbial community structure dynamics is an initial step in establishing a knowledge base for farmers to exploit the soil microbiota to maintain healthy soil for crop production.

Grain legumes in crop rotations under low and variable rainfall: are observed short-term N benefits sustainable?

Increased grain yields are frequently obtained when a cereal follows a grain legume in sequence compared with a cereal-cereal rotation. The biotic (disease break) and abiotic (N supply) components of the observed benefits are identified and methods for differentiating the components are discussed. Annual measurements of the N balance of grain legume-cereal rotations are extremely variable when measured over short time periods and are therefore not useful as indicators of cropping system N sustainability. While measurement of long-term changes in total soil N is a valid index of N sustainability, this approach is impractical. We suggest an alternative avenue for the assessment of N sustainability by using simulation modelling, after validation, which takes climatic and biophysical parameters into account.

Crop types have stronger effects on soil microbial communities and functionalities than biochar or fertilizer during two cycles of legume-cereal rotations of dry land.

The addition of biochar to agricultural fields has been widely studied, but most of these studies have emphasized its effects by growing a single type of crop over short- to long-term time spans. Additionally, a limited number of studies have focused on the soil microbial community composition with respect to biochar addition in legume-cereal crop rotation. In this study, we examined soil microbial community structures by adding biochar (0, 5, and 10tha-1) and fertilizer (nitrogen-N, phosphorous-P and potassium-K) during 2cycles of mash bean and wheat rotations. The results showed that the bacterial (16S rRNA) gene abundance was often increased by biochar addition in the presence of mash bean (Vigna mungo L.) but not wheat. When the soil received fertilizer, the bacterial gene abundance was less responsive to biochar addition. Fungal (ITS rRNA) copy numbers were enhanced by biochar and fertilizer in presence of wheat but were decreased in the presence of mash bean. Fertilizer addition also resulted in less change in ITS genes after biochar addition. Microbial functional groups including Gram+, Gram- and Pseudomonas bacteria were stimulated by biochar or fertilizer only in mash bean soils, while mycorrhizae were significantly increased by biochar in wheat soils. Although biochar addition affected soil properties, microbial community assays were not greatly altered by these physicochemical properties. In conclusion, the crop type played a decisive role, rather than biochar or fertilizer addition, in shaping microbial community structures (16S and ITS phyla) during crop rotation.

Forage Rotations Conserve Diversity of Arbuscular Mycorrhizal Fungi and Soil Fertility.

In the Mediterranean, long-term impact of typical land uses on soil fertility have not been quantified yet on replicated mixed crop-livestock farms and considering the variability of soil texture. Here, we report the effects, after 15 years of practice, of two legume-winter cereal rotations, olive orchards and vineyards on microbiological and chemical indicators of soil fertility and the communities of arbuscular mycorrhizal fungi (AMF). We compare the changes among these four agricultural land-use types to woodland reference sites. Root colonization by AMF of English ryegrass (Lolium perenne L.), a grass that occurred under all land use types, was only half as heavy in biannual berseem clover (Trifolium alexandrinum L.)-winter cereal rotations than in 4-year alfalfa (Medicago sativa L.)-winter cereal rotations. In olive (Olea europaea L.) orchards and vineyards (Vitis vinifera L.), where weeds are controlled by frequent surface tillage, the AMF root colonization of ryegrass was again much lower than in the legume-cereal rotations and at the woodland reference sites. All the microbial parameters and soil organic carbon correlated most strongly with differences in occurrence and relative abundance (β-diversity) of AMF genera in soil. The soil pH and mineral nutrients in soil strongly correlated with differences in AMF root colonization and AMF genus richness (α-diversity) in soil. Diversity of AMF was much less affected by soil texture than land use, while the opposite was true for microbial and chemical soil fertility indicators. Land uses that guaranteed a continuous ground cover of herbaceous plants and that involved only infrequent tillage, such as multiyear alfalfa-winter cereal rotation, allowed members of the AMF genus Scutellospora to persist and remain abundant. On the contrary, under land uses accompanied by frequent tillage and hence discontinuous presence of herbaceous plants, such as tilled olive orchard and vineyard, members of the genus Funneliformis dominated. These results suggest that multiyear alfalfa-winter cereal rotation with active plant growth throughout the year is the least detrimental agricultural land use in soil carbon and AMF abundance and diversity, relative to the woodland reference.

Legume-based rotations have clear economic advantages over cereal monocropping in dry areas

Current land use trends show an increasing preference for monocropping – mostly a consequence of policies and incentives aimed at enhancing the intensification of cereals. This shift has caused some to question whether legume–cereal rotations can remain economically viable options for farmers, particularly in the dry areas. In this paper, we present the results of an endogenous switching regression model which suggests, for the first time, that legume–cereal rotations have clear economic advantages over cereal monocropping. Rotations provide higher yields, gross margins, and consumption of wheat and faba beans. Most past economic analyses on rotation used data from experimental stations or small-sized farmer surveys covering only one season and variety. This study makes an important improvement by employing two-year data from a large sample of 1230 farm households and their 2643 fields cultivated with different varieties of wheat and faba beans in the wheat-based production system of Morocco. Assuming a biennial rotation – the fastest cycle possible in a rainfed dryland system, this paper is also the first to demonstrate that joint adoption of rotations and improved faba bean varieties leads to a two-year average gross margin that is US$537/ha (48%) higher than wheat monocropping. This is the highest economic benefit of all available cropping options. A striking result of the study is that, contrary to common expectations, adopters of rotation did not use lesser amounts of nitrogen fertilizer than those monocropping wheat, thereby undermining the ecological benefits of faba bean–wheat rotations. Given that current average applications are below marginal product-maximizing levels, higher marginal yields of nitrogen fertilizers after rotation help explain farmers’ current behavior. Our results suggest that: 1) promoting improved legume varieties may enhance adoption of rotation; and 2) an economic rationale should be used as the main driver of the rotation agenda in the dry areas.

Performances of Durum Wheat Varieties Under Conventional and No-Chemical Input Management Systems in a Semiarid Mediterranean Environment

Chemical input reduction in agricultural systems is strongly demanded with the aim to improve the quality and the safety of food/feed products in an environmental sustainable perspective. Durum wheat is the most important food crop widely grown across the Mediterranean basin. However, the choice of tailored-genotypes can represent a key strategy in resource limiting conditions. The present study investigated the performance of fourteen commercial durum wheat varieties, in terms of morphologic, productive and quality traits under two cropping systems, conventional (CH) and no-chemical input (NC), for two growing seasons. The NC cropping system affected plant phenology, grain yield, and its components (i.e., ears m−2 and test weight). However, the negative influence exerted by the NC depended by the growing season (significant interaction between growing season and cropping system), which in turn affected the production behavior of genotypes (significant interaction between growing season and genotype). The additive main effect and multiplicative interaction (AMMI) analysis showed that genotype (G) effect explained the 4.3% of the total variability, the environment (E) the 71.7% and the G × E interaction the 9.4%. The AMMI stability value (ASV) indicated that Meridiano, Claudio, Saragolla, and Normanno were the most stable genotypes among environments (combination of years and management systems). An integrated environmental assessment, including a soil nitrogen balance, can help to provide a more holistic approach to the sustainability of the no-chemical Mediterranean cropping systems based on cereal-legume rotation.