Multi-Crop Rotation Research Articles

Soil Organic Carbon Dynamics in the Long-Term Field Experiments with Contrasting Crop Rotations

Trends in soil organic carbon (SOC) were analyzed in the soils from the oldest Czech long-term field experiment, the Prague-Ruzyně Long-Term Fertilizer Experiment, conducted on Haplic Luvisol since 1955. The aim of the work was to compare the long-term dynamics of SOC in contrasting crop rotations and different fertilization regimes. The trial design includes two crop rotations (CR): simple CR with two-year rotation of sugar beet and spring wheat, and multi-crop rotation (MCR) with nine crops. Four fertilization treatments were chosen for SOC analysis: unfertilized control, only mineral fertilization (NPK), farmyard manure application (FYM), as well as FYM and NPK application. SOC content was significantly affected by both fertilization and crop rotation practices. In the simple CR, both the unfertilized control and the NPK treatment exhibited a consistent decline in SOC content over the study period, with percentages decreasing from an initial 1.33% in 1955 to 1.15% and 1.14%, respectively. Although the FYM and FYM + NPK treatments showed an increase in SOC content in the 1990s, a gradual decline was recorded in the last two decades. This decrease was not observed in MCR: positive C balances were recorded in all treatments within MCR, with the largest increase in SOC stock occurring when NPK was combined with FYM. In contrast, over the last decade, C balances have decreased in simple CR for all treatments except FYM. This trend coincides with changes in the local climate, particularly rising temperatures. The results indicate that diversified crop rotations and FYM fertilization are effective in mitigating the negative impacts of changing environmental conditions on SOC stocks.

Impact of 40 Years Use of Different Herbicide Strategies and Crop Rotations on Weed Communities in Two Sites of the Czech Republic

Understanding the impact of farming practices on the composition of weed communities has important implications for the sustainability of weed management strategies. This study analyses data from a 40-year experiment established at two sites in the Czech Republic in 1972. The impact of herbicide strategies on the weed communities was evaluated in multi-crop rotation (MCR) with 50% cereals, and simple crop rotations (SCR) with 75% cereals. The following two herbicide strategies were compared: (1) simple treatment with synthetic auxins only in the simple crop rotation, and (2) targeted herbicide combinations with particular use of sulfonylureas, triazines, ureas and synthetic auxins. Untreated plots were included for reference purposes. Results showed that crop was the major factor determining weed community composition and explained 18% of the total variation in the case of untreated controls. However, herbicide treatment reduced the crop effect to 11%. The highest average increase of Shannon’s diversity index was by 25.4% after 44 years at the untreated plots in SCR, and it decreased by 15.1% at the treated plots in MCR. Weed species evenness € increased at all plots by an average of 23%. Simpson’s dominance index decreased at untreated plots in both crop rotations and plots treated with auxins, with the highest 44.8% decrease at the untreated plots in SCR. On the contrary, Simpson’s index increased by 33,3% on the treated plots in MCR. Herbicide selection depended on the occurrence and density of target weed species, and led to greater decrease in weed diversity and population densities in the diversified crop rotations.

Diversified crop rotations reduce groundwater use and enhance system resilience

Agricultural intensification has increased crop productivity but simplified production and reduced cropping system diversity. In recent decades, the intensified wheat–maize rotation in the North China Plain has sharply decreased the groundwater table, with associated environmental and biodiversity issues. Understanding whether increasing cropping system diversity stabilizes productivity, improves resilience, and reduces adverse environmental impacts is critical. This study quantified the water requirements of nine staple crops from 1960 to 2020, established 15 alternative crop rotations, and evaluated the resilience of each rotation in the Cangzhou area, a typical groundwater deletion funnel area. The results showed that reducing cropping density (harvests per year) from 2 to 1.5 decreased the average annual water requirement and irrigation demand by 14 % and 33 %, respectively. Summer soybean alternated with maize and rotated with wheat did not reduce groundwater use but increased profitability and protein production. Spring mung bean–summer millet-based multi-rotations had higher precipitation coupling degrees (8 % in wet years, 17 % in normal years, and 56 % in dry years) and profitability (1.1–2.4 times) than the wheat–maize rotation. The spring potato–summer millet rotation in one year had the greatest profitability, the highest equivalent yield to wheat, and the highest water use efficiency (WUE), while spring maize rotated with winter wheat–summer soybean performed best for protein content, energy output, and WUEs. This study identified 11 alternative rotations with a higher comprehensive evaluation index than the conventional wheat–maize rotation based on entropy-TOPSIS considering 12 indicators. Spring mungbean is not suitable for inclusion in the crop rotation when solely cultivated in one year due to mismatched rainfall. Beyond wheat and maize, soybean, millet, and potato are promising crops for innovative multi-year multi-crop rotations to enhance crop diversification, maximize system outputs, and minimize groundwater and energy depletion. This study’s analysis could be extended to develop robust and diverse crop rotations with multiple co-benefits in other water-stressed agricultural regions.

Continuous maize cultivation with high nitrogen fertilizers associated with the formation of dried soil layers in the semiarid farmland on the Loess Plateau

• Different land use types were chosen to determine soil desiccation. • Long-term maize cultivation with high yield caused a DSLs in the deep soil layers. • Crop rotations are recommended for maize production in the semiarid environment. Sustainable agriculture ensures food security and combats climate change by minimizing reliance on water resources. Maize ( Zea mays L.) is commonly grown with plastic mulching practice on the Loess Plateau of China, but its impact on soil desiccation is not well understood. We compared the effects of different land-use, including 17-year continuous wheat cultivation, 19-year pea-wheat rotations, 12-year continuous maize cultivation (high yield), 30-year multi-crop rotations, and 9-year continuous maize cultivation (varying yield) under four nitrogen (N) fertilization rates (i.e., 0, 100, 200, and 300 kg N ha −1 ). Average crop evapotranspiration during 2009–2020 for long-term continuous wheat, pea-wheat rotation, high-yielding maize, and multi-crop rotations was 222, 201, 277, and 393 mm, respectively, while average effective precipitation from March to September was 329 mm for all treatments. Continuous high-yielding maize cultivation formed a dry soil layer (DSL) in the deep soil profile (>400 cm), which was not found in other cultivation modes. After 9-year continuous high-yielding maize cultivation, 300 kg N ha −1 applying (20.9 Mg ha −1 biomass yield) formed the DSLs in the 360–960 cm soil profiles, while under 200 kg N ha −1 (20.1 Mg ha −1 biomass yield), the soil water content was almost close to the threshold of DSL in the 600–740 cm soil depth; while under 0 and 100 kg N ha −1 (<15 Mg ha −1 biomass yield), the DSL was not found along the soil profile, indicating that DSL formation under continuous maize cultivation was is driven by high N rates (or high yield level). These results suggest that long-term high-yielding maize cultivation with plastic mulching causes severe soil water depletion, resulting in the formation of a DSL in the deep soil profile. To maintain productivity, farmers should not be encouraged to carry out long-term continuous cropping of high-yielding maize in the semiarid environment on the Loess Plateau.

Future climate change impacts on grain yield and groundwater use under different cropping systems in the North China Plain

Crop production in the North China Plain (NCP) is heavily influenced by the unfolding climate change and water shortage. Groundwater overdraft for irrigation in this region has caused serious ecological and environmental problems. Cropping systems adjustment offers an effective approach for the sustainable use of groundwater. However, the assessment of the impacts of future climate change on crop production and water consumption under different cropping systems with/without straw mulching has not been reported in the NCP. In this study, we applied the well validated APSIM model to explore the implementation of five cropping systems (i.e., two maturities per year, 1Y2MS0; three maturities per two year without (with) straw mulching during the fallow period, 2Y3MS0 (2Y3MS1); and one maturity per year without (with) straw mulching during the fallow period, 1Y1MS0 (1Y1MS1)). Statistical downscaled daily climate data based on 33 global climate models (GCMs) were used to drive APSIM to simulate crop phenology, yield and water use under future climate change. We found that cropping system adjustment significantly reduced the amount of water required for irrigation, thereby decreasing groundwater overdraft to a certain extent. Straw mulching could have mitigating effect on groundwater overdraft. Multi-GCMs ensemble means show an increase in temperature, precipitation and solar radiation in the future. Under future climate change scenarios, the phenological date (e.g. flower and maturity dates) of maize and wheat were advanced due to climate warming. Our simulated results indicated that future climate change would have negative impact on maize yield across all cropping systems but have positive impact on wheat yield under most climate change scenarios. Both irrigation and groundwater overdraft reduced in the future due to decreased evapotranspiration and increased precipitation. We concluded that 2Y3MS1 would be the optimum cropping system to balance crop yield and groundwater overdraft. This knowledge can inform the development of improved regional impact assessments of the sustainability of multi-crop rotation systems.

Cost and effectiveness of in-season strategies for coping with weather variability in Pakistan's agriculture

Crops are vulnerable to weather hazards throughout the growth season, with periods of heightened risk described as critical moments. Farmers have a number of ex-ante and in-season options for coping with these events, and ex-post adjustments to farm-household portfolios to further limit the impact on livelihoods if these options fail. Adaptation-related research has focussed mainly on ex-ante or ex-post coping strategies, because in-season approaches tend to be seen as a given, meaning their cost effectiveness is ignored. Based on detailed survey data collected from 287 households in four of the main cropping systems in Pakistan, this study evaluates the impact pathways of hazards and the cost effectiveness of in-season coping strategies. Yield losses varied by 10–30% for 43% of the cases and by 31–50% for another 39%, with the most severe losses caused by the compounding effect of two hazards in one crop season or if both crops in a multi-crop rotation were affected simultaneously. In-season coping options were mostly restricted to the early crop stages and constrained by a short window of time for the response. The application of in-season coping strategies resulted in a yield recovery of 40–95%, with an additional cost of 4–34% of the value of recovered yield. The major critical moments identified were the harvest season, with farming often affected by un-seasonal precipitation, and the germination stage, with an additional high risk for low temperatures at high altitude. A better understanding of the differentiated risks and effectiveness of in-season coping strategies could support the promotion of sustainable crop production in similar agro-ecologies. Moreover, the effectiveness of present-day coping strategies, rather than the use of coping approaches itself, could signal a potential ability to adjust to future climate change.

Managing food and bioenergy crops with declining groundwater levels in the North China Plain

Managing the complex demands on available energy, food and water is a fundamental challenge for a world with increasingly tenuous resource pools. The North China Plain’s groundwater crisis has become increasingly serious due to decades-long over-exploitation for irrigation to pursue high grain yield. This combined challenge motivated investigation of ways to mitigate the groundwater table decline while fostering the use of renewable bioenergy resources. To provide insights about tradeoffs among water, food and energy, we performed a six-year experiment from 2010 to 2015 in the North China Plain where groundwater use, biomass and biofuel production and water use efficiency were compared for four cropping systems. They are winter wheat-summer maize (WM, grains, 1-year cycle), ryegrass–sweet sorghum (RS, forage plus bioenergy crops, 1-year cycle), winter wheat–summer maize→ ryegrass–sweet sorghum (WMRS, forage, bioenergy plus grain crops, 2-year cycle), and perennial switchgrass (SG, bioenergy crop). Actual evapotranspiration (ETa) and recharge to groundwater were calculated and validated using observed soil moisture contents. Results showed ETa of the cropping systems were statistically similar ranging from 694 to 730 mm yr−1 with the exception of switchgrass which was significantly less at 504 mm yr-1. The water table was projected to decline by about 1.3 m yr-1 for all three multi-crop rotations and 0.4 m yr-1 for switchgrass. In terms of bioethanol production per unit land and per unit ETa, the ryegrass-sweet sorghum (RS) rotation performed best with 25.0 m3 ha-1 and 5.7 L m-3 outperforming the yearly winter wheat–summer maize (WM) rotation (11.7 m3 ha-1 and 3.3 L m-3) and switchgrass (11.4 m3 ha-1 and 2.6 L m-3). The multiple year rotation of winter wheat–summer maize→ ryegrass–sweet sorghum (WMRS) yielded 16.9 m3 bioethanol per hectare and 4.3 L m-3 bioethanol per m3ETa. When optimizing bioethanol against net groundwater depletion, RS and switchgrass outperformed the two grain-based rotations with 15.5 L and 14.4 L of bioethanol per m3 of depleted groundwater, ahead of WMRS at 10.9 L m-3 and WM at 9.1 L m-3. These results are significant for setting governmental policies on sustainable use of groundwater by various crop mixes.

Adapting crop rotations to climate change in regional impact modelling assessments

The environmental and economic sustainability of future cropping systems depends on adaptation to climate change. Adaptation studies commonly rely on agricultural systems models to integrate multiple components of production systems such as crops, weather, soil and farmers' management decisions. Previous adaptation studies have mostly focused on isolated monocultures. However, in many agricultural regions worldwide, multi-crop rotations better represent local production systems. It is unclear how adaptation interventions influence crops grown in sequences. We develop a catchment-scale assessment to investigate the effects of tactical adaptations (choice of genotype and sowing date) on yield and underlying crop-soil factors of rotations. Based on locally surveyed data, a silage-maize followed by catch-crop-wheat rotation was simulated with the APSIM model for the RCP 8.5 emission scenario, two time periods (1985–2004 and 2080–2100) and six climate models across the Kaituna catchment in New Zealand. Results showed that direction and magnitude of climate change impacts, and the response to adaptation, varied spatially and were affected by rotation carryover effects due to agronomical (e.g. timing of sowing and harvesting) and soil (e.g. residual nitrogen, N) aspects. For example, by adapting maize to early-sowing dates under a warmer climate, there was an advance in catch crop establishment which enhanced residual soil N uptake. This dynamics, however, differed with local environment and choice of short- or long-cycle maize genotypes. Adaptation was insufficient to neutralize rotation yield losses in lowlands but consistently enhanced yield gains in highlands, where other constraints limited arable cropping. The positive responses to adaptation were mainly due to increases in solar radiation interception across the entire growth season. These results provide deeper insights on the dynamics of climate change impacts for crop rotation systems. Such knowledge can be used to develop improved regional impact assessments for situations where multi-crop rotations better represent predominant agricultural systems.

Arable Crop Rotations Under Abiotic Stress: A Dynamic Economic Model

Break crops and multi-crop rotations are common in arable farm management, and the soil quality inherited from a previous crop is one of the parameters that determine the gross margin that is achieved with a given crop from a given parcel of land. In previous work we developed a dynamic economic model to calculate the potential yield and gross margin of a set of crops grown in a selection of typical rotation scenarios, and we reported use of the model to calculate coexistence costs for GM maize grown in a crop rotation. The model predicts economic effects of pest and weed pressures in monthly time steps.Validation of the model in respect of specific traits is proceeding as data from trials with novel crop varieties is published. Alongside this aspect of the validation process, we are able to incorporate data representing the economic impact of abiotic stresses on conventional crops, and then use the model to predict the cumulative gross margin achievable from a sequence of conventional crops grown at varying levels of abiotic stress. We report new progress with this aspect of model validation.In this paper, we report the further development of the model to take account of abiotic stress arising from drought, flood, heat or frost; such stresses being introduced in addition to variable pest and weed pressure. The main purpose is to assess the economic incentive for arable farmers to adopt novel crop varieties having multiple ‘stacked’ traits introduced by means of various biotechnological tools available to crop breeders.

Quantification of Biomass Feedstock Availability to a Biorefinery Based on Multi-Crop Rotation Cropping Systems Using a GIS-Based Method

<abstract> <bold><sc>Abstract.</sc></bold> The feasibility of utilizing cellulosic biomass as an energy feedstock is dominated by factors such as facility location, feedstock availability, and transportation cost. Our previous case study showed improvements in quantification of feedstock availability for a biorefinery by introducing the effect of field-level yield variance and variable residue removal rates as improvement parameters into the GIS-based analysis. Even though the improved GIS-based method enhanced quantification of feedstock availability with the addition of the improvement parameters, a biorefinery would most likely procure more than one feedstock type. In this case study, quantification of feedstock availability based on multi-crop rotation cropping systems was done using the previously improved GIS-based variable residue removal (VRR) method. We observed on average a 3,793 ±5,733 DT per service area difference when increasing the number of crops used to estimate feedstock quantification. The supplementary use of crop-specific VRR rates affected residue availability, given that a crop’s residue removal rate is influenced by crop yield, crop rotation, soil characteristics, as well as field location and management. It was also observed that the amount of available hectares of the three main crops analyzed in this case study affected residue availability. Corn represented 26.2% (440,636 ha; 1,101,591 acres), sorghum represented 12.9% (217,432 ha; 543,579 acres), and wheat represented 60.9% (1,024,607 ha; 2,561,518 acres) of the hectares in the study area. The validation study showed the importance of taking into account the seasonal availability of crop residue when estimating procurement service areas, given that in some cases feedstock requirements were not met.

Computing Hybrid Rotation Period of Cotton-Rice and Cotton-Others

The aim of this study was to investigate the use of a remote-sensing model to compute a hybrid rotation period of multi-crop rotation in large area. The model was constructed to compute the hybrid rotation period of cotton-rice and cotton-others of 38 towns in XingHua City, Jiangsu Province, China. The rotation periods for cotton-rice and cotton-others were computed as 2.09 and 3.38 years using the data from satellite remote sensing images. The results were shown to lead to a hybrid rotation period of cotton-rice and cotton-others of 1.24 years. This indicates that there is a possibility of managing multi-crop rotation in large area from hybrid rotation periods and suggests that it is possible to measure crop growth status in large area with hybrid rotation periods to make management decision for crop diseases.

Assessment of Multiple Management Systems in the Upper Midwest

Independently, reduced tillage, multicrop rotations, and organic fertilization are expected to enhance soil biological properties; outcomes are less understood when these management strategies are integrated with conventional or organic system management. Over 9 yr, soil biological properties of microbial biomass C (MBC) and N (MBN) and soluble organic C (SolC) and total soluble N (SolN) were measured to evaluate these practices. A full factorial arrangement within each management system of the following strategies were used: 2‐yr vs. 4‐yr rotation; conventional tillage (CT) vs. strip tillage (ST); and unfertilized vs. fertilized with inorganic fertilizer or manure in the conventional and organic systems, respectively. Parsing out independent effects from integrated strategies demonstrated that across all years, MBC and MBN were not influenced by system management but were higher in 4‐yr than 2‐yr rotations, ST than CT, and fertilized than unfertilized treatments; SolC and SolN were greater in fertilized treatments and SolN greater in CT treatments. Independent strategies, however, reacted differently when integrated under the two management systems. Under conventional system management, MBC increased with time only when ST was combined with a 4‐yr rotation, regardless of fertilization strategy; whereas, under organic system management, MBC increased with time in all ST treatments regardless of rotation or fertilization strategy. Results confirmed expectations that reduced tillage and increased rotation diversity positively impacted measured soil parameters, but inorganic vs. organic fertilizer resulted in few differences. Selecting and using individual strategies to achieve positive soil changes will depend on system‐level management and how strategies are integrated.

Irrigation management and investment under saline, limited drainage conditions: 2. Characterization of optimal decision rules

Optimal decision rules and dynamics are characterized for the irrigation management model in the previous paper (Knapp, this issue (a)). For a constant crop and irrigation system, the decision rules are concave in E[s] and SD[s]. That is, seasonal water applications first increase as these variables increase, and then possibly decrease. Optimal water applications are observed to be decreasing in the correlation coefficient, although the effect is small. Optimal water applications and soil salinity follow a cyclical time path with a multicrop rotation. The decision rules for applied water are also found to vary for the same crop depending on place within the crop rotation. A range of irrigation systems are efficient depending on prices and other parameters. Investment dynamics are generally a constant type of irrigation system with possibly an initial transition period of another system type. More complex investment behavior is observed with constrained water supplies.

Field Machinery Requirements as Influenced by Crop Rotations and Tillage Practices

ABSTRACT MACHINERY requirements (number and size of each machinery component) and costs were determined for 29 cash crop production systems of southern Michi-gan. Man-hours of labor, labor distribution during the year, and fuel requirements were also calculated. The cash crop production systems considered included ten representative crop rotations involving corn, soybeans, field beans, wheat, and alfalfa, and three tillage systemsmoldboard plow, chisel plow, and no-till. Multicrop balanced rotations increased machinery utilization, and thus decreased (a) machinery require-ments on a unit crop area basis by as much as. half, (b) machinery investment by as much as 40 percent, and (c) annual machinery related costs by as much as 30 percent over single-crop rotations. Tillage intensity influenced tractor power by as much as 65 percent and fuel require-ment by as much as 35 percent, but the effect on ma-chinery investment and machinery related costs was gen-erally less than 15 percent for multicrop rotations. This was so because at the reduced tillage intensity different crops were raised using different tillage systems and, therefore, more implements were required.