Agricultural Management Options Research Articles

Irrigation of young grapefruits with desalinated seawater: Agronomic and economic outcomes

Given the current scarcity of freshwater resources, it is imperative to explore new agricultural management options to sustainably enhance food production. Desalinated seawater (DSW) presents a promising solution for irrigation in water-stressed regions. However, its application in perennial crops has been poorly assessed, potentially posing challenges to existing cultivation practices due to higher associated costs, salinity, and the presence of potentially harmful elements, notably boron (B). To address these uncertainties, a three-year experiment was conducted to evaluate the short-term effects of irrigation with DSW on a ‘Rio Red’ grapefruit orchard. Four irrigation treatments were assessed: DSW, freshwater (FW), a 1:1 mixture of DSW and FW (MW), and DSW with reduced B concentration (DSW–B). At present, the young age of the trees (3.5 years) and their grafting onto a five-year-old rootstock at the beginning of the experiment likely facilitated rapid foliar mass development and prevented the accumulation of phytotoxic elements up to critical levels. However, local DSW consistently exceeded recommended citrus thresholds for B (0.5 mg L–1), sodium (Na+; 115 mg L–1), and chloride (Cl–; 250 mg L–1) in irrigation water, resulting in significant concentrations of B (2.1 mg kg–1), Na+ (504 mg L–1) and Cl– (476 mg L–1) in soil. Moreover, these levels led to concentrations in leaves close to defined thresholds in the case of Na+ (0.25 g 100 g–1), and exceeded them in the case of B (>250 mg kg–1). Although fruit quality remained unaffected, variability in yield among trees and the cost disparity between water resources, resulted in slight fluctuations in the income-outcome balance during initial cultivation years. Our findings offer insights into the irrigation of sensitive crops with DSW, aimed at mitigating potential soil and plant harm from early accumulation of phytotoxic elements. Further research is warranted to explore the impact of both single and sustained DSW usage for irrigation purposes.

BODIUM—A systemic approach to model the dynamics of soil functions

AbstractThe increasing demand for biomass for food, animal feed, fibre and bioenergy requires optimization of soil productivity, while at the same time, protecting other soil functions such as nutrient cycling and buffering, carbon storage, habitat for biological activity and water filter and storage. Therefore, one of the main challenges for sustainable agriculture is to produce high yields while maintaining all the other soil functions. Mechanistic simulation models are an essential tool to fully understand and predict the complex interactions between physical, biological and chemical processes of soils that generate those functions. We developed a soil model to simulate the impact of various agricultural management options and climate change on soil functions by integrating the relevant processes mechanistically and in a systemic way. As a special feature, we include the dynamics of soil structure induced by tillage and biological activity, which is especially relevant in arable soils. The model operates on a 1D soil profile consisting of a number of discrete layers with dynamic thickness. We demonstrate the model performance by simulating crop growth, root growth, nutrient and water uptake, nitrogen cycling, soil organic matter turnover, microbial activity, water distribution and soil structure dynamics in a long‐term field experiment including different crops and different types and levels of fertilization. The model is able to capture essential features that are measured regularly including crop yield, soil organic carbon, and soil nitrogen. In this way, the plausibility of the implemented processes and their interactions is confirmed. Furthermore, we present the results of explorative simulations comparing scenarios with and without tillage events to analyse the effect of soil structure on soil functions. Since the model is process‐based, we are confident that the model can also be used to predict quantities that have not been measured or to estimate the effect of management measures and climate states not yet been observed. The model thus has the potential to predict the site‐specific impact of management decisions on soil functions, which is of great importance for the development of a sustainable agriculture that is currently also on the agenda of the ‘Green Deal’ at the European level.

Impacts of agricultural intensification on soil erosion and sustainability of olive groves in Alentejo (Portugal)

ContextOlive groves are key features of Iberian Mediterranean landscapes. With the intensification of olive grove production, some negative environmental impacts on soils must be considered to achieve farm sustainability.ObjectivesTo estimate, theoretically and empirically, soil erosion in olive groves of Alentejo (Portugal) considering different planting densities and soil managements (i.e. conventional, integrated, organic), and related impacts on soil loss and farm sustainability.MethodsSoil erosion was empirically calculated using sediment traps. Soil loss was modelled using the Universal Soil Loss Equation (USLE) model. The impact of erosion on farm sustainability was assessed by simulating future projections to 100 and 500 years.ResultsAn overestimation of theoretical erosion rates for all olive management models compared to the empirical results was observed. Plant cover strongly contributed to reduce soil loss. Temporal simulations based on experimental data showed a longer sustainability of intensive groves than expected according to theoretical values.ConclusionsDespite the negative impacts of intensive agriculture, this study highlights that it is essential to consider soil management impacts on erosion, an aspect that influences farm sustainability, regardless of planting density. Future studies should expand our experiments across a wider sample and locations of olive groves, to better discern how olive sustainability is impacted by different agricultural management options and decisions.

Identifying and Comparing Easily Accessible Frameworks for Assessing Soil Organic Matter Functioning

Soil organic matter (SOM) stocks are crucial for soil fertility and food provision and also contribute to climate change adaptation and mitigation. However, assessing SOM changes in cropping systems is difficult due to the varying quantity and quality of input data. SOM processes have been described by several models, but these are complex and require high amounts of input data. In this work, we identified and selected frameworks that simulate SOM pools and stocks as well as the effects of different management practices. We also required that the frameworks be easily accessible for farm-related end users and require limited and accessible amounts of input data. In all, six frameworks met our inclusion criteria: SOCRATES (Soil Organic Carbon Reserves and Transformations in EcoSystems), CCB (CANDY and-Carbon Balance), AMG, CENTURY, CQESTR, and RothC (Rothamsted Carbon Model). We collected information on these frameworks and compared them in terms of their accessibility, the model time steps used, the nutrient cycles included in the simulation, the number of SOM pools, and the agricultural management options included. Our results showed that CCB was the most robust of the frameworks considered, while AMG, CQESTR, and RothC performed the least well. However, all frameworks have strengths which may match the specific requirements and abilities of individual users.

Strategies for agricultural production management based on land, water and carbon footprints on the Qinghai-Tibet Plateau

Agricultural production consumes land and water resources, and contributes to greenhouse gas emissions. Optimizing agricultural management to reduce environmental impacts is essential for regional ecological security. An evaluation framework was applied to assess the greenhouse gas emissions, water utilization, and land use of agricultural production in a typical agricultural region of the Huangshui River Basin on the Qinghai-Tibet Plateau, using footprint analysis. The results showed that agricultural production released 1.73 × 109 kg carbon equivalent (CO2-eq), and used 8.39 × 108 m3 of water and 2.96 × 105 ha of land. For the carbon footprint, agricultural material inputs (such as electricity, machinery, diesel, and nitrogen fertilizer) were the largest emission sources. For the water footprint, the blue water footprint was larger than the green water footprint. In addition, suitable management options were explored by establishing six scenarios according to the key factors influencing greenhouse gas emissions and water consumption. For technical strategy management options, using cleaner electricity in irrigation can reduce greenhouse gas emissions by 25.53%. Comprehensive strategies, including fertilizer application optimization and technical strategy management, proved to be more effective and reduced greenhouse gas emissions by 32.41%. The results of this study help to determine optimal agricultural management options for achieving both food security and environmental sustainability in agricultural areas on the Qinghai-Tibet Plateau.

The importance of nitrogen for net carbon sequestration when considering natural climate solutions.

To store substantial amounts of carbon in natural climate solutions the strong interlinkages between carbon and nitrogen cycling must be considered. There are many agricultural management options for increasing soil organic carbon stocks but each approach must be evaluated in context of the full, net greenhouse gas balance. This requires a detailed understanding of the implications of increased nitrogen demand to store organic forms of carbon in soil, on potential nitrous oxide emissions in particular.

Can N2 O emissions offset the benefits from soil organic carbon storage?

To respect the Paris agreement targeting a limitation of global warming below 2°C by 2100, and possibly below 1.5°C, drastic reductions of greenhouse gas emissions are mandatory but not sufficient. Large-scale deployment of other climate mitigation strategies is also necessary. Among these, increasing soil organic carbon (SOC) stocks is an important lever because carbon in soils can be stored for long periods and land management options to achieve this already exist and have been widely tested. However, agricultural soils are also an important source of nitrous oxide (N2 O), a powerful greenhouse gas, and increasing SOC may influence N2 O emissions, likely causing an increase in many cases, thus tending to offset the climate change benefit from increased SOC storage. Here we review the main agricultural management options for increasing SOC stocks. We evaluate the amount of SOC that can be stored as well as resulting changes in N2 O emissions to better estimate the climate benefits of these management options. Based on quantitative data obtained from published meta-analyses and from our current level of understanding, we conclude that the climate mitigation induced by increased SOC storage is generally overestimated if associated N2 O emissions are not considered but, with the exception of reduced tillage, is never fully offset. Some options (e.g. biochar or non-pyrogenic C amendment application) may even decrease N2 O emissions.

Leveraging agroecology for solutions in food, energy, and water

Global agriculture is facing growing challenges at the nexus of interconnected food, energy and water systems, including but not limited to persistent food insecurity and diet-related diseases; growing demands for energy and consequences for climate change; and declining water resources, water pollution, floods and droughts. Further, soil degradation and biodiversity loss are both triggers for and consequences of these problems. In this commentary, we argue that expanding agroecological principles, tools, and technologies and enhancing biological diversity can address these challenges and achieve better socioeconomic outcomes. Agroecology is often described as multi- or transdiscplinary, and applies ecological principles to the design and management of agricultural systems through scientific research, practice and collective action. While agroecology has roots in the study of food systems, agricultural land use has many direct and indirect linkages to water and energy systems that could benefit from agroecological insights, including use of water resources and the development of bio-based energy products. Although opportunities from the science and the practice of agroecology transcend national boundaries, obstacles to widespread adoption vary. In this article, we therefore focus on the United States, where key barriers include a shortage of research funds, limited supporting infrastructure, and cultural obstacles. Nevertheless, simply scaling up current models of agricultural production and land use practices will not solve many of the issues specific to food related challenges nor would such an approach address related energy and water concerns. We conclude that a first critical step to discovering solutions at the food, energy, water nexus will be to move past yield as a sole measure of success in agricultural systems, and call for more holistic considerations of the co-benefits and tradeoffs of different agricultural management options, particularly as they relate to environmental and equity outcomes.

Evaluating the Impact of Legacy P and Agricultural Conservation Practices on Nutrient Loads from the Maumee River Watershed.

The recent resurgence of hypoxia and harmful algal blooms in Lake Erie, driven substantially by phosphorus loads from agriculture, have led the United States and Canada to begin developing plans to meet new phosphorus load targets. To provide insight into which agricultural management options could help reach these targets, we tested alternative agricultural-land-use and land-management scenarios on phosphorus loads to Lake Erie. These scenarios highlight certain constraints on phosphorus load reductions from changes in the Maumee River Watershed (MRW), which contributes roughly half of the phosphorus load to the lake's western basin. We evaluate the effects on phosphorus loads under nutrient management strategies, reduction of fertilizer applications, employing vegetative buffers, and implementing widespread cover crops and alternative cropping changes. Results indicate that even if fertilizer application ceased, it may take years to see desired decreases in phosphorus loads, especially if we experience greater spring precipitation or snowmelt. Scenarios also indicate that widespread conversions to perennial crops that may be used for biofuel production are capable of substantially reducing phosphorus loads. This work demonstrates that a combination of legacy phosphorus, land management, land use, and climate should all be considered when seeking phosphorus-loading solutions.

A modeling study on mitigation of N2O emissions and NO3 leaching at different agricultural sites across Europe using LandscapeDNDC

The identification of site-specific agricultural management practices in order to maximize yield while minimizing environmental nitrogen losses remains in the center of environmental pollution research. Here, we used the biogeochemical model LandscapeDNDC to explore different agricultural practices with regard to their potential to reduce soil N2O emissions and NO3 leaching while maintaining yields. In a first step, the model was tested against observations of N2O emissions, NO3 leaching, soil micrometeorology as well as crop growth for eight European cropland and grassland sites. Across sites, LandscapeDNDC predicts very well mean N2O emissions (r2=0.99) and simulates the magnitude and general temporal dynamics of soil inorganic nitrogen pools. For the assessment of site-specific mitigation potentials of environmental nitrogen losses a Monte Carlo optimization technique considering different agricultural management options (i.e., timing of planting, harvest and fertilization, amount of applied fertilizer as well as residue management) was used. The identified optimized field management practices reduce N2O emissions and NO3 leaching from croplands on average by 21% and 31%, respectively. Likewise, average reductions of 55% for N2O emissions and 16% for NO3 leaching are estimated for grasslands. For mitigating environmental loss - while maintaining yield levels - it was most important to reduce fertilizer application rates by in average 10%. Our analyses indicate that yield scaled N2O emissions and NO3 leaching indicate possible improvements of nitrogen use efficiencies in European farming systems. Moreover, the applied optimization approach can be used also in a prognostic way to predict optimal timings and fertilization options (rates and splitting) upon accurate weather forecasts combined with the knowledge of modeled soil nutrient availability and plant nitrogen demand.

Monte Carlo-based calibration and uncertainty analysis of a coupled plant growth and hydrological model

Abstract. Computer simulations are widely used to support decision making and planning in the agriculture sector. On the one hand, many plant growth models use simplified hydrological processes and structures – for example, by the use of a small number of soil layers or by the application of simple water flow approaches. On the other hand, in many hydrological models plant growth processes are poorly represented. Hence, fully coupled models with a high degree of process representation would allow for a more detailed analysis of the dynamic behaviour of the soil–plant interface. We coupled two of such high-process-oriented independent models and calibrated both models simultaneously. The catchment modelling framework (CMF) simulated soil hydrology based on the Richards equation and the van Genuchten–Mualem model of the soil hydraulic properties. CMF was coupled with the plant growth modelling framework (PMF), which predicts plant growth on the basis of radiation use efficiency, degree days, water shortage and dynamic root biomass allocation. The Monte Carlo-based generalized likelihood uncertainty estimation (GLUE) method was applied to parameterize the coupled model and to investigate the related uncertainty of model predictions. Overall, 19 model parameters (4 for CMF and 15 for PMF) were analysed through 2 × 106 model runs randomly drawn from a uniform distribution. The model was applied to three sites with different management in Müncheberg (Germany) for the simulation of winter wheat (Triticum aestivum L.) in a cross-validation experiment. Field observations for model evaluation included soil water content and the dry matter of roots, storages, stems and leaves. The shape parameter of the retention curve n was highly constrained, whereas other parameters of the retention curve showed a large equifinality. We attribute this slightly poorer model performance to missing leaf senescence, which is currently not implemented in PMF. The most constrained parameters for the plant growth model were the radiation-use efficiency and the base temperature. Cross validation helped to identify deficits in the model structure, pointing out the need for including agricultural management options in the coupled model.

Agricultural Management Options for Climate Variability and Change: High-Residue Cover Crops

While decision making in agriculture involves many aspects beyond climate, including economics, social factors, and policy considerations, climate-related risks are a primary source of yield and income variability. This 4-page fact sheet focuses on the use of high-biomass winter cover crops to improve production systems. Written by Joel Love, Jed Dillard, Kirk Brock, Daniel Dourte, and Clyde Fraisse, and published by the UF Department of Agricultural and Biological Engineering, August 2012.

Agricultural Management Options for Climate Variability and Change: Sod-Based Rotation

A sod-based rotation is when a producer adapts a conventional peanut/cotton rotation by growing a perennial grass, such as bahiagrass, during two years of the rotation. The perennial grass can be grazed, cut for hay or harvested for seed for additional income. Using a sod-based rotation can improve soil water-holding capacity and potentially reduce impacts of dry spells and droughts. This 4-page fact sheet was written by David Wright, Jim Marois, Clyde Fraisse, and Daniel Dourte, and published by the UF Department of Agricultural and Biological Engineering, August 2012.

Agricultural Management Options for Climate Variability and Change: AgroClimate

AgroClimate is a website providing climate information and decision-support tools to producers throughout the Southeastern United States. With information from the site, producers can develop a strategy for the coming season and track climate conditions that affect crop development and yield. This 4-page fact sheet was written by Clyde Fraisse and published by the UF Department of Agricultural and Biological Engineering, August 2012.

Agricultural Management Options for Climate Variability and Change: Microirrigation

Microirrigation is the slow, frequent application of water directly to relatively small areas adjacent to individual plants through emitters placed along a water delivery line. A leading advantage of microirrigation is that evaporation that does not contribute to plant growth happens much less than with sprinkler irrigation. This 5-page fact sheet was written by Lincoln Zotarelli, Clyde Fraisse, and Daniel Dourte, and published by the UF Department of Horticultural Sciences, July 2012. HS1203/HS1203: Agricultural Management Options for Climate Variability and Change: Microirrigation (ufl.edu)

Agricultural Management Options for Climate Variability and Change: Variable-Rate Irrigation

Most fields are not uniform because of natural variations in soil type or topography. When water is applied uniformly to a field, some areas of the field may be overwatered while other areas may remain too dry. Variable-rate irrigation technology gives farmers an automated method to vary rates of irrigation water based on the individual management zones within a field and avoid irrigating roadways, waterways, wetlands, and other non-farmed areas within a pivot. This 3-page fact sheet was written by Calvin Perry, Clyde Fraisse, and Daniel Dourte, and published by the UF Department of Agricultural and Biological Engineering, July 2012.

Agricultural Management Options for Climate Variability and Change: Conservation Tillage

This 4-page fact sheet focuses on the use of conservation tillage in crop production systems as a strategy to minimize the risks associated with climate variability and change and to improve resource-use efficiency. Written by Kip Balkcom, Leah Duzy, Daniel Dourte, and Clyde Fraisse, and published by the UF Department of Agricultural and Biological Engineering, June 2012.

Global change and agricultural management options for groundwater sustainability

According to the general circulation models (CGMs) for future climate projections, a temperature increase, precipitation decrease, and an increase in the variability of extreme events may be expected in the future, likely reducing available water resources. For the western Mediterranean, future climate change projections indicate that temperature increase may range from 1.5°C to 3.6°C, and the precipitation decline will reach between 10% and 20%, which may result in a significant reduction of natural groundwater recharge. With the use of modelling tools, the amount of groundwater recharge under different climate change scenarios and varying agricultural management practices can be predicted, and water budget attributes can be estimated, which may allow for quantifying impacts, and assist in defining adaptation strategies. For the Inca–Sa Pobla basin (Balearic Islands, Spain), under future climate change projections, agricultural management alternatives of crop type distribution and irrigation demands are required for planned adaptation strategies. In the area, where irrigation water for agricultural practices originates from groundwater resources, adaptation measures based on a change from mixed crops to potatoes and a 20% decrease of agricultural land cultivation have proven to be efficient for the hydrologic system and associated wetland sustainability.

Impact of selected agricultural management options on the reduction of nitrogen loads in three representative meso scale catchments in Central Germany

Nitrogen inputs into surface waters from diffuse sources are still unduly high and the assessment of mitigation measures is associated with large uncertainties. The objective of this paper is to investigate selected agricultural management scenarios on nitrogen loads and to assess the impact of differing catchment characteristics in central Germany. A new modelling approach, which simulates spatially distributed N-transport and transformation processes in soil and groundwater, was applied to three meso scale catchments with strongly deviating climate, soil and topography conditions. The approach uses the integrated modelling framework JAMS to link an agro-ecosystem, a rainfall-runoff and a groundwater nitrogen transport model. Different agricultural management measures with deviating levels of acceptance were analysed in the three study catchments. N-leaching rates in all three catchments varied with soil type, the lowest leaching rates being obtained for loess soil catchment (18.5 kg nitrate N ha − 1 yr − 1 ) and the highest for the sandy soils catchment (41.2 kg nitrate N ha − 1 yr − 1 ). The simulated baseflow nitrogen concentrations varied between the catchments from 1 to 6 mg N l − 1 , reflecting the nitrogen reduction capacity of the subsurfaces. The management scenarios showed that the highest N leaching reduction could be achieved by good site-adapted agricultural management options. Nitrogen retention in the subsurface did not alter the ranking of the management scenarios calculated as losses from the soil zone. The reduction effect depended strongly on site specific conditions, especially climate, soil variety and the regional formation of the crop rotations.

Long-term impact of reduced tillage and residue management on soil carbon stabilization: Implications for conservation agriculture on contrasting soils

Residue retention and reduced tillage are both conservation agricultural management options that may enhance soil organic carbon (SOC) stabilization in tropical soils. Therefore, we evaluated the effects of long-term tillage and residue management on SOC dynamics in a Chromic Luvisol (red clay soil) and Areni-Gleyic Luvisol (sandy soil) in Zimbabwe. At the time of sampling the soils had been under conventional tillage (CT), mulch ripping (MR), clean ripping (CR) and tied ridging (TR) for 9 years. Soil was fully dispersed and separated into 212–2000 μm (coarse sand), 53–212 μm (fine sand), 20–53 μm (coarse silt), 5–20 μm (fine silt) and 0–5 μm (clay) size fractions. The whole soil and size fractions were analyzed for C content. Conventional tillage treatments had the least amount of SOC, with 14.9 mg C g −1 soil and 4.2 mg C g −1 soil for the red clay and sandy soils, respectively. The highest SOC content was 6.8 mg C g −1 soil in the sandy soil under MR, whereas for the red clay soil, TR had the highest SOC content of 20.4 mg C g −1 soil. Organic C in the size fractions increased with decreasing size of the fractions. In both soils, the smallest response to management was observed in the clay size fractions, confirming that this size fraction is the most stable. The coarse sand-size fraction was most responsive to management in the sandy soil where MR had 42% more organic C than CR, suggesting that SOC contents of this fraction are predominantly controlled by amounts of C input. In contrast, the fine sand fraction was the most responsive fraction in the red clay soil with a 66% greater C content in the TR than CT. This result suggests that tillage disturbance is the dominant factor reducing C stabilization in a clayey soil, probably by reducing C stabilization within microaggregates. In conclusion, developing viable conservation agriculture practices to optimize SOC contents and long-term agroecosystem sustainability should prioritize the maintenance of C inputs ( e.g. residue retention) to coarse textured soils, but should focus on the reduction of SOC decomposition ( e.g. through reduced tillage) in fine textured soils.