Three-year Rotation Research Articles

Adapting to diversified garlic-maize rotation systems by adjusting nitrogen application: Assessing crop yield, nitrogen utilization, and nitrogen footprint

Diversified crop rotation is crucial for maintaining sustainable agricultural production by improving resource use efficiency, balancing soil nutrients, and preserving biodiversity. Despite these benefits, there is a notable gap in research concerning the nutrient transport characteristics in cash crop-grain rotation systems. This study was to investigate: (i) the nitrogen (N) uptake and distribution among the different plant organs in rotation crops; (ii) the N footprint in different growth seasons in response to crop N fertilization and residual N in the soil; and (iii) the influence of environmental factors on the productivity and N footprint in cash-grain rotation systems. In the three-year rotation system, N fertilizer was applied at the rates of 220, 175, and 130 kg N eq ha−1 for maize, and 300 and 240 kg N eq ha−1 for garlic. Results showed that maintaining a high N application rate during the garlic season and appropriately reducing it during the maize season (G300M175) enhanced N transfer to the grains of maize, increasing maize N use efficiency by 18.9%, while simultaneously increasing garlic dry matter and N accumulation. While the maize yield remained stable, garlic yield decreased with the reduced N rate, resulting in a significant reduction in N footprint. Water supplies (precipitation and irrigation) positively impacted dry matter accumulation, N absorption and yield, while reducing N footprint in both crops. Elevated air temperature favored maize yield but hindered garlic production and raised garlic N footprint. Although N fertilizer increased N footprint per unit land area (NFa), it decreased the N footprint per unit N uptake by crops (NFn) while boosting crop yields. Maintaining a suitable N input rate for cash crops in previous season while reducing N input in the following season staple crops can enhance the whole systems’ productivity while decreasing the nitrogen footprint.

Sustainable alternative to irrigated maize monoculture in a maize-dominated cropped area: Lessons learned from a system experiment

Maize is the most-produced food crop in the world and is grown in intensive rotations or in monoculture (continuous maize) systems. As maize production has expanded massively across the world, many concerns have emerged about its local environmental and other global impacts. Agronomists have designed innovative cropping systems and assessed them using system experiments to make arable systems more sustainable. However, knowledge is still lacking on the sustainability of innovative cropping systems compared to highly intensive systems such as irrigated maize-based monoculture. Here, we present the assessment results of a nine-year system experiment in Alsace, France, developed to compare an innovative system based on a diversified rotation and innovative management practices (three-year rotation of maize/soybean/winter wheat (plus a cover crop) combined with reduced tillage) with a continuous maize reference system. The results cover a six-year assessment period following an initial three-year design period. Classic criteria, such as profitability, workload, pesticide use, fossil energy consumption and nitrate leaching, were assessed along with other less studied criteria, such as pesticide leaching risk, soil structure, soil chemical quality and soil biological activity. Sustainability – which includes environmental, social and economic dimensions – was assessed with the MASC 2.0 method. Overall sustainability was substantially enhanced in the innovative system (5 out of 7 sustainability classes) in comparison with the low level of the reference system (2 out of 7). This was due to a clear improvement in the environmental performance (from 2 out of 5 to 5 out of 5) while social performance was high in both systems (4 out of 5) and economic performance was low (2 out of 5) due to very low contribution to economic development. Nevertheless, the innovative system had a major drawback: lower profitability, especially when scenarios included high maize prices. Furthermore, herbicide use on maize was higher in the innovative system than in the reference one. Avenues for progress, such as encouraging stakeholder participation at the assessment stage or additional innovations such as multiple cropping, are suggested.

Effects of BC on metal uptake by crops (availability) and the vertical migration behavior in soil: A 3-year field experiments of crop rotation

Biochar (BC) has been substantiated to effectively reduce the available content of heavy metals (HMs) in soil-plant system; however, the risk of biochar (BC)derived dissolved organic matter (DOM) induced metal vertical migration has not been well documented, especially in the long-term field conditions. Therefore, this study investigated HM vertical migration ecological risks and the long-term effectiveness of the amendment of biochar in the three successive years of field trials during the rotation system. The results revealed that biochar application could increase soil pH and DOM with a decrease in soil CaCl2 extractable pool for Pb, Cu, and Cd. Furthermore, the results indicated a significant decrease in acid phosphatase activities and an increase in urease and catalase activities in the soil. Cucumber was shown to be safe during a three-year rotation system in the field. These results suggest that BC has the potential to enhance soil environment and crop yields. BC derived DOM-specific substances were identified using parallel factor analysis of excitation-emission matrix in deep soil (0–60 cm). The study incorporated HM concentration fluctuations in deep soils, providing an additional interpretation of DOM and co-migration of HMs.The environmental risk associated with the increase in DOM hydrophobicity should not be ignored by employing BC for soil HM remediation applications. The study enhances understanding of biochar-derived DOM's migration and stabilization mechanisms on heavy metals, providing guidelines for its use as a soil amendment.

Two decades of carbon dynamics in an actively-managed, naturally-regenerated longleaf/slash pine forest

Naturally regenerated pine ecosystems cover 11.7 Mha of the southeastern United States, comprising 13.8% of the forested land, and represent an important component in the carbon balance for the region. These forests are exposed to strong climatic variability from extreme multiyear droughts to above average precipitation years, many are actively managed with prescribed fire and some modification of tree density by cutting. This study is unique in assessing the effects of management and climatic variability for two decades on the carbon (C) dynamics and long-term net ecosystem C balance (NECB) for an actively-managed naturally regenerated pine ecosystem. We used 21 years of eddy covariance estimates of net ecosystem C production (NEP), combined with periodic tree inventories, understory biomass and forest floor assessments. Forest management included six prescribed fire cycles on a three-year rotation beginning in the third year of the study, and a preparatory cut which reduced basal area by 20% from 17.05 ± 0.66 m2/ha during the spring of 2016. The mean annual NEP was 3.32 ± 1.37 Mg C/ha yr−1, with a range of 5.35 Mg C/ha (1.30 to 6.65 Mg C ha/yr), was not significantly affected by fire and was mainly controlled by water availability. A combination of aboveground C assessments (tree and understory) and NEP indicates that C stored belowground accounted for 23% of NEP, with part of this used to support aboveground understory growth after fire. Net ecosystem carbon balance (NECB, integrated NEP and C losses from management) fluctuated in a range of 15.5 Mg Cha−1 (6.7 to −8.8 Mg C ha -1) and was sensitive to management. However, a higher NECB during the second decade than in the first (15.3 Mg C/ha vs. 2.7 Mg C/ha) reflected increased NEP (40 Mg C/ha vs. 25.4 Mg C/ha) as it responded to a greater water availability, despite similar amounts of C lost from management activities during both decades. At the end of the 21 years study, the ecosystem had incorporated 22.6 Mg C ha -1, indicating that actively managed naturally regenerated pine ecosystems in the region can mitigate C dioxide emissions under a broad range of climatic conditions, reduce wildfire risks, while providing numerous ecosystem services.

Multi-criteria assessment of cropping systems for the sustainable intensification in the Pampas

CONTEXTThe transformation of cropping systems towards sustainable intensification (SI) is essential in order to meet the demands of society. In the Pampas region of Argentina, most agricultural research has focused on crop ecophysiology and agronomic factors, although what seems to be lacking is an integrated evaluation of cropping systems to determine their alignment with SI trends. Multi-criteria analysis (MCDA) methods provide a formal framework to assess trade-offs between production and sustainability, rendering them useful for SI analysis. OBJECTIVEThis paper aims to compare and rank the cropping systems available in the rolling Pampas, the corn belt of Argentina, based on their alignment with SI trajectories, using the multi-criteria decision model “Preference Ranking Organization Methods for Enrichment Evaluations” (PROMETHEE). METHODSWe used information from a mid-term experiment conducted in Pergamino, Buenos Aires, Argentina, to compare ten cropping systems over five consecutive years. These systems resulted from combining three crop sequences with either fallow or cover crops during the winter, and were grown using two different management practices. Sixteen economic, socioeconomic, and environmental criteria were defined to assess each of the cropping systems. We combined PROMETHEE with the Analytical Hierarchy Process (AHP) to compare the cropping systems. We considered two different decision-making profiles: one obtained through interviews with farmers, and the other based on interviews with agents involved in sustainable production systems at the Ministry of Agriculture of Argentina. RESULTS AND CONCLUSIONSWe ranked the cropping systems assessed according to how well they aligned with SI, the system that combines improving profits with reduced environmental impact. We found that the three-year rotation sequence of wheat/soybean-corn-soybean is the most aligned to the sustainable intensification option among the feasible crop sequences implemented in the rolling Pampas region. Furthermore, our results indicate that cover crops provide environmental benefits, but the associated costs discourage their implementation when the farmer profile focuses on maximizing economic benefits. SIGNIFICANCEWe emphasize the importance of integrally analyzing cropping systems. Our findings confirm the advantages noted in prior studies and provide a more thorough evaluation of wheat/soybean-corn-soybean three-year sequence. Finally, our work demonstrates the value of PROMETHEE multi-criteria analysis in assessing the SI of cropping systems. This tool could be a useful aid in facilitating discussions among farmers, consultants and other stakeholders, in the search for sustainable intensification pathways.

Management practices during the renewal year affect the carbon balance of a boreal legume grassland

Evaluating the net ecosystem carbon balance (NECB) of legume-based grasslands is crucial for optimizing grassland management and assessing the sustainability of the milk and beef industries. This study investigated the NECB of a boreal legume grassland in eastern Finland from May 2017 to May 2020, covering the entire three-year rotation cycle. We found that the grassland showed interannual variability in carbon sequestration, fixing 220 g C m−2 in the first year, 334 g C m−2 in the second year, and losing 146 g C m−2 in the last year during the grassland renewal period. The study also examined the effects of mineral nitrogen fertilizer and digestate residue addition on the NECB of the grassland. No significant differences in net ecosystem carbon dioxide exchange were observed between the two treatments, but the application of digestate slurry increased the NECB, suggesting that organic fertilizers could potentially enhance carbon sequestration and sustain ecosystem services. In conclusion, our findings emphasize the importance of developing climate-friendly renovation management practices that maximize the photosynthetic period in boreal legume grasslands. These practices, combined with the use of organic fertilizers, can contribute to improved carbon sequestration and support the sustainability of milk and beef industries that rely on grasslands.

Rotation of Cotton (Gossypium hirsutum) Cultivars and Fallow on Yield and Rotylenchulus reniformis.

A three-year rotation of cotton (Gossypium hirsutum) cultivars either resistant (R) or susceptible (S) to Rotylenchulus reniformis and fallow (F) was examined for effect on cotton yield and nematode density. In year 1, 2, and 3, the resistant cultivar (DP 2143NR B3XF) yielded 78, 77, and 113% higher than the susceptible cultivar (DP 2044 B3XF). Fallow in year 1 followed by S in year 2 (F1S2) improved yield in year 2 by 24% compared with S1S2, but not as much as R1S2 (41% yield increase over S1S2). One year of fallow followed by R (F1R2) had lower yield in year 2 (11% reduction) than R1R2. The highest yield after three years of these rotations occurred with R1R2R3, followed by R1S2R3 (17% less yield) and F1F2S3 (35% less yield). Rotylenchulus reniformis density in soil averaged 57, 65, and 70% lower (year 1, 2, 3, respectively) in R1R2R3 compared with S1S2S3. In years 1 and 2, LOG10 transformed nematode density (LREN) was lower in F1, and F1F2, than for all other combinations. In year 3, the lowest LREN were associated with R1R2R3, F1S2F3, and F1F2S3. The highest LREN were associated with F1R2S3, F1S2S3, S1S2S3, R1R2S3, and R1S2S3. The combination of higher yield and lower nematode density will be a strong incentive for producers to use the R. reniformis resistant cultivars continuously.

Supply chain optimization of sustainable aviation fuel from carinata in the Southeastern United States

Carinata is a purpose-grown oilseed feedstock for renewable fuels, including sustainable aviation fuel (SAF) that can replace conventional aviation fuel (CAF). Given carinata is a new crop in the Southeastern United States, it is crucial to analyze its sustainability from a supply chain perspective. This study developed a mixed-integer linear programming (MILP) model and simulated it for 20 years, starting from a farm (county-level data) and ending at the airport. About 2.06 million ha in Alabama, Florida, and Georgia combined were found suitable for carinata production. Given the three-year rotation period, about 0.69 million hectares can be cultivated annually, approximately 65% of which was in Georgia. About 2.4% of the combined SAF annual demand of four major airports (about 210 thousand t) in the study area is satisfied at that level of carinata cultivation. However, all available SAF was supplied to the Atlanta airport as this decision minimizes the supply chain cost. A total of 1343 storage units, one oil extraction mill, and one biorefinery were needed to meet the overall demand. We found that SW Georgia is the top supplier of carinata seeds. The unit cost of production and carbon intensity were estimated to be $0.89 L-1 (or $26.79 GJ−1) and 0.91 kg CO2e L−1 (or 27.28 kg CO2e GJ−1), respectively. This carbon intensity of carinata-based SAF was 67.8% lower than that of CAF. With variations included in SAF demand, yield, and soil carbon sequestration, carbon savings remained between 66.5% and 67.8%. Given the GHG advantage of SAF over CAF, there is justification for subsidies required to make SAF competitive.

Tillage intensity and plant rhizosphere selection shape bacterial-archaeal assemblage diversity and nitrogen cycling genes

Agroecosystem management practices, plant-microbe interactions, and climate are all factors that influence soil microbial community diversity and functionality. Herein, we assessed diversity of soil bacterial-archaeal assemblages and denitrification gene markers in a long-term tillage field experiment. We evaluated bulk and rhizosphere soils from two crop years (corn and soybean) of a three-year rotation of corn-soybean-small grain + cover crop. Soil samples were collected at three growth stages from corn and soybean plants and across three tillage practices that had been applied every year for 40 years. Tillage practices represented three levels of disturbance intensity ranging from low (no-till) to intermediate (chisel-disk) to high (moldboard plow) intensities. Bacterial assemblage diversity differed in soils having contrasting tillage histories and from bulk or rhizosphere soil (compartments), crop year, and growth stage. Compared to plowed and chisel-disked soils, no-till soils had lower abundances of denitrification genes, higher abundances of genes for dissimilatory nitrate reduction to ammonium (DNRA), and higher abundances of family-level taxa associated with archaeal nitrification and anammox. Soybean rhizospheres exerted stronger selection on bacterial-archaeal composition and diversity relative to corn rhizospheres. Abundances of N genes were grouped by factors related to weather, as well as management and soil compartment, which could impact activity related to denitrification and DNRA. Low intensity tillage may provide an option to reduce potential ‘hot spots’ or ‘hot moments’ for N losses in agricultural soils, although weather and crop type are also important factors that can influence how tillage affects microbial assemblages and microbial N use.

Impact of diversification and intensification of crop rotation (DICR) in soil bacterial microbiota in on-farm study after four and seven years

No-till agricultural diversification and intensification of crop rotations (DICR) effects on soil biological properties were studied in an on-farm study. DICR stands for increasing soil cultivation period and consequent reduction of fallow times by using different winter and summer crops, including cover crops, in two and three-year rotation schemes. Five different levels of DICR were tested -typical local rotation, intermediate rotation, high intensification with grasses, high intensification with legumes, and a continuous multispecies pasture-, and replicated at three different agricultural farms situated in the Argentinean Pampa. The soils were analyzed at four and seven years after DICR started. The on-farm studies were established at each site in a plot of ca. fifty hectares with a typical local rotation history and evaluated after four and seven years of changes. The impact on prokaryotic soil communities was measured by 16S rRNA gene sequencing. Overall, the sustained DICR showed a progressive effect with reduced Bray-Curtis dissimilarities at second sampling. At the phylum level, Actinobacteria, Bacteroidetes, Verrucomicrobia, BCR1, and WS3 increased with the level of DICR while Acidobacteria, Firmicutes, Gemmatimonadetes, OD1, and TM7 showed the opposite trend. Selected taxa based on LEfSe detection were associated with typical historical rotation after the four years and pasture after the seven years, expressing the cumulative effect of DICR. Bacterial communities' structures were associated with plant stubble and crop yield. Understanding how more sustainable practices such as DICR shift the soil microbiota can assist in designing agricultural systems that increase soil health, C sequestration, and crop yield.

Risk Assessment and Area-Wide Crop Rotation to Keep Western Corn Rootworm below Damage Thresholds and Avoid Insecticide Use in European Maize Production.

Simple SummaryDiabrotica virgifera virgifera LeConte, the Western corn rootworm (WCR), is a maize-specific pest that has been a serious threat in Europe since the mid-1990s. To properly implement integrated pest management, it is necessary to identify the key factors associated with risks of crop damage from WCR and to evaluate the effectiveness of area-wide strategies based on agronomic measures, such as crop rotation, in reducing those risks. In Italy and Croatia, a survey of agronomic and cultural factors in fields damaged by WCR allowed us to determine that the beetle population size accounts for most of the risk of maize damage from WCR. Crop rotation (without insecticide use), both structural and flexible, was the most effective strategy for keeping WCR populations below the damage threshold. This indicates that WCR management can be carried out in accordance with European Union regulations to limit or avoid insecticide treatments and reduce environmental impacts.The Western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, has been a serious quarantine pest to maize in Europe since the mid-1990s. The integrated pest management of WCR requires an accurate knowledge of the factors that contribute most to risks of crop damage, as well as knowledge of effective area-wide strategies based on agronomic measures, such as crop rotation. In Italy and Croatia, agronomic and cultural factors in fields damaged by WCR were evaluated through a long-term survey. Based on the survey results, high-WCR densities contribute most to risks of damage to maize. Extensive field research in north-eastern Italy compared large areas of continuous maize production with areas under different crop rotation systems (i.e., a structural one with one-time maize planting in a three-year rotation and a flexible one with continuous maize planting interrupted when beetle populations exceed the threshold). The objective was to evaluate the effectiveness of different rotation regimes as possible best practices for WCR management. Captures of beetles in yellow sticky traps, root damage, larval densities, and damage to maize plants (e.g., lodging) were assessed at the center of each area. The results demonstrated the both structural and flexible crop rotation systems were effective strategies for maintaining WCR below damage threshold densities without the need for insecticides.

Annual productivity of cropping sequences: Responses to increased intensification levels

Annual productivity of croplands can be increased by intensifying cropping sequences and fine-tuning agronomic management, improving the ratio between seasonal grain yield and annual available resources. The aims of this study were to evaluate, for different crop sequences and agronomic practices, (i) grain yield (GY), and energy of GY (EY) on annual basis; (ii) the relative contribution of each crop to the annual GY and EY of the crop sequences; and (iii) the maximum attainable annual EY. In a five-year field experiment at the central Rolling Pampa of Argentina, three crop sequences: soybean mono-cropping (Sy), a two-year rotation alternating maize and soybean (Mz-Sy), and a three-year rotation including wheat/soybean, maize, and soybean (Wt/Sy-Mz-Sy) were evaluated under the presence of either fallow (F) or cover crops (CC) during winter, and under two agronomic systems: conventional (CM) and intensified management (IM). For EY, Mz-Sy and Wt/Sy-Mz-Sy sequences greatly surpassed (P < 0.01) Sy (78% and 86% higher) across all years. The CC negatively affected (P < 0.001) the annual GY of the sequences by mostly affecting maize GY (−14% than under F), but this effect varied with the experimental year (rainfall levels) and CC composition (grass/legume proportion). The annual GY of the Mz-Sy (6.47 Mg ha−1) and Wt/Sy-Mz-Sy (6.69 Mg ha−1) sequences increased (P < 0.001) in the IM system compared to CM (5.33 and 5.64 Mg ha−1). In addition, under IM the penalty of CC on the annual GY of the crop sequences was lower (−7%) than under CM (−14%). From the combination of crop sequences and agronomic systems, the highest annual EY corresponded to the more intensified Wt/Sy-Mz-Sy sequence under IM (176 GJ ha−1), doubling the lowest EY obtained by soybean mono-cropping under CM (87 GJ ha−1). This result highlights the opportunity for intensification of cropping sequence and agronomic management to increase the annual productivity of the existing cropping area.

Analysis of cropping pattern in black soil region of Northeast China based on geo-information Tupu.

Different cropping patterns have their own economic and ecological significance. Developing cropping patterns suitable for local conditions is needed to protect and make good use of black soils. At present, the cropping patterns and their spatial characteristics in the black soil region of Northeast China is poorly understood. Based on the crop classification data in 2017-2019, we used geo-information Tupu methods, distribution index model, and bivariate spatial autocorrelation to examine the cropping patterns. The results showed that: 1) The main cropping patterns in the black soil region of Northeast China were continuous maize cropping, continuous rice cropping, continuous soybean cropping, and maize-soybean rotation, accounting for 38.3%, 18.5%, 10.3% and 26.0%, respectively. The maize-soybean rotation included maize-soybean two-year rotation, maize-maize-soybean three-year rotation, and soybean-soybean-maize three-year rotation, accounting for 44.1%, 34.5% and 21.4% of the rotation area, respectively. 2) Various cropping patterns had obviously horizontal differentiation. For instance, continuous maize cropping had very obvious gradient differentiation characteristics in temperature and humidity, but soybean continuous cropping and maize-soybean rotation showed no gradient differentiation, while continuous rice cropping had gradient differentiation only in humidity. 3) Various cropping patterns had obviously spatial clustering characteristics. They had spatial transition characteristics from soybean continuous cropping, soybean-soybean-maize three-year rotation, maize-soybean two-year rotation, maize-maize-soybean three-year rotation, to continuous maize cropping. The cropping pattern in black soil region of Northeast China was dominated by continuous cropping. Understanding its distribution pattern can provide a basis for future spatial optimization of crop rotation.

Time-course foliar dynamics of poplar short rotation plantations under Mediterranean conditions. Responses to different water scenarios

Poplar (Populus spp.) Short Rotation Coppice (SRC) systems are characterized by high short-term biomass productivity and play a key role in promoting employment in rural areas as well as supplying environmental benefits. However, in the context of climate change with expected reduced water availability in the Mediterranean area, the productivity of these plantations may be seriously limited. In this regard, the aim of this work is to analyse the monthly dynamic responses of relevant variables at foliar level throughout the entire first rotation of a poplar short rotation plantation under two water scenarios: optimal scenario (with irrigation to field capacity (FC)) versus restrictive scenario (with 50% FC irrigation).This data came from 590 trees in a poplar short rotation plantation of the highly productive genotype ‘AF2‘. LAImax values of 2.39, 7.47 and 9.34 were found for the three-year rotation cycle, pointing to significantly lower values after the establishment year under the restrictive water scenario. SLA mean values displayed a downward trend, with 12.25 m2 kg−1, 10.82 m2 kg−1 and 10.47 m2 kg−1 for years 1, 2 and 3 respectively, no significant differences being observed between water scenarios. NPK foliar concentrations decreased over the rotation, being the values lower under the restrictive scenario. Additionally, the selected genotype, ‘AF2’, displayed tight stomatal control under conditions of water stress, maintaining high photosynthetic levels.The responses observed in this study can potentially be used to better understand the behavior of these variables which most affect production of poplar plantations in face of climate change.

Characterizing Dominant Field-Scale Cropping Sequences for a Potato and Vegetable Growing Region in Central Wisconsin

Crop rotations are known to improve soil health by replenishing lost nutrients, increasing organic matter, improving microbial activity, and reducing disease risk and weed pressure. We characterized the spatial distribution of crops and dominant field-scale cropping sequences from 2008 to 2019 for the Wisconsin Central Sands (WCS) region, a major producer of potato and vegetables in the U.S. The dominant two- and three-year rotations were determined, with an additional focus on assessing regional potato rotation management. Our results suggest corn and soybean are the two most widely planted crops, occurring on 67% and 36% of all agricultural land at least once during the study period. The most frequent two- and three-year crop rotations include corn, soybean, alfalfa, sweet corn, potato, and beans, with continuous corn being the most dominant two- and three-year rotations (13.2% and 8.5% of agricultural land, respectively). While four- and five-year rotations for potato are recommended to combat pest and disease pressure, 23.2% and 65.9% of potato fields returned to that crop in rotation after two and three years, respectively. Furthermore, 5.6% of potato fields were planted continuously with that crop. Given potato’s high nitrogen (N) fertilizer requirements, the prevalence of sandy soils, and ongoing water quality issues, adopting more widespread use of four- or five-year rotations of potato with crops that require zero or less N fertilizer could reduce groundwater nitrate concentrations and improve water quality.

Weed species diversity and shifts in conservation agriculture-based crop rotation systems on the Highveld area of South Africa

The occurrence and infestation levels of weed species are known to vary greatly within conservation agriculture (CA) systems as weed species will react differently to different habitats. Two on-farm CA trial sites, near Buffelsvallei and Viljoenskroon respectively, were established during 2008/09. The objective of this study was to observe the species diversity and potential species shifts between conventional and CA based rotation systems. Monoculture maize (MM) under both conventional tillage (CT) and CA crop systems was accordingly evaluated against two-year and three-year rotation CA systems of maize with cowpea and sunflower respectively. Pearl millet was the third crop in the three-year rotation systems. Visual surveys of weed species were conducted annually at both trial sites and data for the 2012–2016 evaluation period presented regarding the weed spectrum observed. Weed spectrums differed significantly between the two localities, but weed species diversity remained constant across seasons. A weed species shift was recorded for the sandy loam soil where numbers of Commelina benghalensis L. increased rapidly after three years, whilst Crotalaria sphaerocarpa DC numbers more than doubled. New weed species, such as Helichrysum argyrosphaerum DC and Vernonia poskeana Vatke and Hildebr., also started to germinate at the sandy loam soil trial site.

Willow Biomass as Energy Feedstock: The Effect of Habitat, Genotype and Harvest Rotation on Thermophysical Properties and Elemental Composition

Willow biomass is used as a bioenergy source in various conversion technologies. It is noteworthy that apart from the beneficial environmental impact of a willow plantation, the biomass quality is also very important as it has an impact on the effectiveness of its use and emissions produced in various bioenergy technologies. Therefore, this study analysed the thermophysical properties and elemental composition of 15 genotypes of willow biomass from two plantations situated in the north of Poland, harvested in two consecutive three-year rotations. The differences in the moisture content, ash content and the lower heating value were mainly determined by the genotype, i.e., by genetic factors. In contrast, the content of carbon, nitrogen, sulphur and hydrogen was determined by the location (environmental factors), but also by the genotype, and by a combination of these factors. The following were the mean levels of the willow biomass characteristics, regardless of the location, genotype and harvest rotation: 48.9% moisture content, 1.26% d.m. ash content, 19.4% d.m. fixed carbon, 79.4% d.m. volatile matter, 19.53 MJ kg−1 d.m. higher heating value, 8.20 MJ kg−1 lower heating value, 52.90% d.m. carbon, 6.23% d.m. hydrogen, 0.032% d.m. sulphur, 0.42% d.m. nitrogen. The present research has shown that the selection of the willow genotype is important for the quality of biomass as energy feedstock. However, plantation location, as well as successive harvest rotations, can have a significant impact on the biomass elemental composition.

Enzymatic Activity of Soil under Spelt Grown in An Organic Farming System in Poland’s Temperate Climate

Wheat spelt is a very valuable plant, especially in organic farming. Its high nutritional values combined with low soil and climate requirements increase the interest in growing spelt in various soils. Spelt can be grown in different soil types, including sandy, wet, poor, non-draining and low-fertility soils. It is well adapted to cold climate. Compared to common wheat, it requires less nutrients and is more competitive against weeds. Activities of enzymes in soil under winter spelt have not been studied yet. We sought to determine whether the choice of varieties will also shape the enzymatic activities in different soil types and whether these activities will be the same under different climatic conditions of 2007, 2010 and 2013 year. The aim of this field experiment was to assess the impact of growing different winter spelt varieties (Oberkulmer Rotkorn, Franckenkorn, Schwabenkorn, Ostro) on the enzymatic activity on two different soil complexes. In the years 2007–2013, two three-year rotations of the experiment were carried out (the first ended in 2010 and the second in 2013). Spelt was cultivated in an organic system. Physicochemical properties of the two different types of soil after three and six years of the experiment were compared to the soil properties before the experiment. The catalase activity ranged between 3.33 and 6.75 µmol H2O2 g−1 d.m. min.−1, the dehydrogenase activity ranged between 1.6 and 87.7 nmol TPF g−1 d.m. 24 h−1, and the arylsulfatase activity ranged between 37.5 and 157 µmol pNF g−1 d.m. h−1. The enzymatic activity in the soil depended on the type of soil (as a rule, the activity was higher in a stagnic luvisol than in a haplic cambisol) and on the spelt variety (although no variety had a clear beneficial effect on the activities of all enzymes). Spelt cultivation in an organic system led to an increase of enzymatic activity in a stagnic luvisol, but not always in a haplic cambisol soil type.

Effect of Crop Rotations and Continuous Fertilization on the Status of Silicon (Si) Available in Soil in a 97-Year Permanent Experiment

ABSTRACT This work aims to study the status of silicon (Si) as a plant nutrient in the soil of Bahtim long-term field experiment in Egypt under the effect of crop rotations system and continuous fertilization. The experiment has been set up since 1912 based on two main factors: (1) crop rotations: mono-cropping (MC), two-year rotation (2Y-R), and three-year rotation (3Y-R), and (2) Fertilization: mineral nitrogen N, phosphorus P, potassium K, and organic farmyard manure FYM. Available N, P, K, and Si in soil were estimated. Productivity of soil was evaluated using Berseem (Trifolium alexndrinum L.) cultivated and harvested in 2019. The plant-available Si (PAS) in soil decreased significantly compared to the control C in case of MC by 70.26%, 2Y-R by 85.09%, and 3Y-R by 92.65% in the direction of N > NP > NPK. Mineral fertilization decreased the PAS significantly by 12.84% N, 29.52% NP, 78.45% NPK compared to the control C in the order of MC > 2Y-R > 3Y-R. Berseem yield (t ha−1) increased significantly compared with the control C following the order C < N < NP < NPK. The most significant increase in the yield was recorded for the NPK treatments by 224.04%, and 200% in case of MC, 2Y-R, 3Y-R, respectively.

Friends or foes? Population dynamics of beneficial and detrimental aerial arthropods under Conservation Agriculture

Arthropod pest control is one of the most critical agronomic practices in cereal-based cropping systems. Cropping systems that preserve or promote biological pest control agents are more desirable. Data collected from a long-term trial at the Monze Farmer Training Centre (MFTC) from 2009 to 2012 was used to compare effects of different Conservation Agriculture (CA) systems with conventional practices (CP) on arthropod species diversity and populations with specific emphasis on beneficial and detrimental aerial arthropods. Up to 13 arthropod orders comprising of 40 species were identified in the cropping systems and their population density differed in years and cropping systems. Higher diversity was observed in CA systems in all years based on the Shannon-Weiner indices ranging from 0.4 to 2. However, a CP system with no rotations (CP-M) showed comparable results in the year with low rainfall. Community evenness increased in the same year with a value of 0.46. More beneficial and detrimental arthropods were recorded in a CA system with a three-year rotation of maize, cotton and sunnhemp reaching up to 9533 individuals ha−1. The CP-M recorded the highest increase in detrimental arthropods from 2009 to 2012. A canonical correspondence analysis did not show a clear-cut association of both CA and CP systems with either beneficial or detrimental arthropods. However, associations were more driven by seasonal effects. Reduced soil disturbance, crop residue retention and crop diversity in CA systems preferentially attracted beneficial arthropods while preserving existing favourable arthropods. Conventional tillage systems often disturbed arthropod habitats, disrupted their life cycles leading to lower biological activity. Increased biodiversity from CA systems may therefore support biological control.