Cropland, Competing Land Use, and Food Security Implications: Seven-Decade Case Analysis of USA
Mpanga and Koomson, 2025
Abstract
Land is a finite global resource supporting the growing population with food, shelter, recreation, and other environmental benefits. The United States has over 10% of global arable land, contributing to domestic and global food security. The number of farms in the United States has steadily declined with a relatively stable average farm size. Increasing population growth, pressure on food production and environmental sustainability are concerns for cropland decline and food security. This study analyzed the effects of competing land use, agricultural innovation and technology, climate change, and government policy on cropland. Seven decades (1945–2017) of United States Department of Agriculture (USDA) Census of Agriculture datasets were used as a case study to analyze drivers of cropland changes. The total amount of cropland recorded a 13% reduction in 2017 from 1945. Cropland used for pasture decreased by 72%, representing the most substantial proportional decline among the cropland categories. Competing land uses to cropland such as rural parks and wildlife increased over 1000%, urbanized land increased by 395%, and land designated for defense and industrial areas rose by 13% by 2017. The divergence between total factor productivity and farm inputs suggests that productivity gains were driven primarily by technological advancements rather than increased resource use. Linkages were drawn from several studies on climate change and population growth’s negative impact on cropland, whereas government policies and priorities can either influence cropland decline or increase, based on how the policies are structured. This study underscores a strategic planning approach that incorporates technological innovation, climate adaptation, and sustainable land management to balance agricultural output with competing land needs without compromising food security for the growing global population.
Link to the article: https://www.mdpi.com/2071-1050/17/18/8352
Fishpond Water Potential on Vineyard Soil Health: An Exploratory Study of a Circular System
​Mpanga et al 2024
Abstract: Climate variabilities continue to hinder sustainable food production with an increasing need to use resources such as water and soil efficiently. The quest for these efficiencies in agriculture systems drives innovations among farmers. However, limited data on farm practices, such as irrigating with fishpond water and their effects on soil health, hinder their adoption as climate-smart innovations. In a nearly twenty-year-old vineyard with two distinct irrigation practices (irrigation with recycled fishpond water and irrigation with ditch water), this study was carried out as an exploratory study to investigate the influence of recycling fishpond water on soil health parameters and yield. Soil samples were taken from two different irrigation fields in summer and winter for lab analysis on soil health parameters (organic matter and carbon, nitrogen, phosphorus, microbial biomass, and microbial respiration). Averages over the two seasons of field measurements indicate that long-term irrigation using recycling fishpond water increased the measured soil health parameters (organic matter (13%), organic carbon (30%), nitrogen (17%), phosphorus (46%), microbial biomass (18%), and microbial respiration (56%)) in both summer and winter months when compared to fields receiving just ditchwater irrigation. Using water in a way that can improve soil health increases biodiversity and improves the efficiency of our limited water resources in semi-arid agricultural lands, and this strategy is a climate-smart tool that can help reduce water risks in dry agricultural regions such as Arizona.
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​​Journal and link to publication: Horticulturae 2024, 10(4), 390; https://doi.org/10.3390/horticulturae10040390
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A Decade of Irrigation Water use trends in Southwestern USA: The Role of Irrigation Technology, Best Management Practices, and Outreach Education Programs
Isaac K. Mpanga and John Idowu
Abstract
Irrigation water is crucial for farm operations in the world, with irrigated lands contributing about 40% to food and fiber production. In semi-arid regions such as the Southwestern United States, the demand for irrigation water has increased due to population growth, rising temperatures, and severe drought events in the region. Irrigation plays a vital role in the economies of southwestern states and requires comparative studies to understand the current situation and to propose possible improvement strategies. This study investigated the trend of irrigated cropland, the quantity of irrigation water use, irrigation technology, scheduling decisions, and irrigation outreach using data from 2007 and 2017 United States Department of Agriculture (USDA) National Agriculture Statistics Service (NASS) census. Harvested cropland in the region remained the same with minimal increase in total irrigated land (1%) and the quantity of irrigated water used (2%). However, gravity irrigation methods reduced significantly by 12%, with a 71% increase in the use of drip irrigation systems. The increase in the adoption of soil moisture sensors (55%), plant sensors (107%), government schedules (29%), and supplier’s schedules (50%) for irrigation scheduling decisions, did not translate to a reduction in irrigation water use at the regional level. However, at the state level within the same period, Arizona recorded an increase in irrigated cropland by 10% and harvested cropland by 9%, with a reduction in the quantity of irrigation water used (-5%). The gains in Arizona could be associated with the combined effects of improved irrigation technologies and the use of best management decisions, which could serve as a model for prudent water use in the southwest. There is a need to increase the effort in science-based education and extension programming on integrated approaches that emphasize both irrigation technology and the best management practices, which include seed selection for drought-tolerant crops.
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Journal: Agriculture Water Management
DOI: 10.1016/j.agwat.2020.106438
The Form of N Supply Determines Plant Growth Promotion by P-Solubilizing Microorganisms in Maize
Authors: Isaac Kwadwo Mpanga, Peteh Mehdi Nkebiwe, Mira Kuhlmann, Vincenza Cozzolino, Alessandro Piccolo, Jörg Geistlinger 6, Nils Berger, Uwe Ludewig, Günter Neumann
Abstract
Phosphate-(P)-solubilizing microorganisms (PSM) are important drivers of P cycling in natural and agro-ecosystems. Their use as plant inoculants to improve P acquisition of crops has been investigated for decades. However, limited reproducibility of the expected effects, particularly under field conditions, remains a major challenge. This study demonstrates that the form of nitrogen fertilization has a significant impact on the performance of various fungal and bacterial PSM inoculants in maize grown on neutral to alkaline soils with limited P availability. Under these conditions, a high soil pH-buffering capacity frequently limits the efficiency of nutrient mobilization, mediated by plant roots and microorganisms via rhizosphere acidification. In a soil pH range between 7.0 and 8.0, nitrate fertilization promoting rhizosphere alkalinisation further aggravates this problem. Accordingly, in greenhouse experiments, six strains of Pseudomonas, Bacillus, Paenibacillus, Streptomyces, and Penicillium with proven P-solubilizing potential, completely failed to promote P acquisition in maize grown on a calcareous Loess sub-soil pH 7.6 with nitrate fertilization and rock phosphate (Rock-P) as a sparingly soluble P source. However, after replacement of nitrate fertilization by ammonium, stabilized with the nitrification inhibitor 3,4-dimethylpyrazole-phosphate (DMPP), five out of seven investigated PSM inoculants (comprising 12 fungal and bacterial PSM strains) exerted beneficial effects on plant growth and reached up to 88% of the shoot biomass production of a control supplied with soluble triple-superphosphate (TSP). Stabilized ammonium combined with PSM-inoculants improved P acquisition (Trichoderma harzianum T22, Pseudomonas sp. DMSZ 13134), while other strains particularly stimulated root growth (T. harzianum OMG16, Bacillus amyloliquefaciens FZB42), which promoted the acquisition also of other mineral nutrients, such as N, K, and Mn. A similar effect was recorded under field conditions on an alkaline clay-loam soil pH 8.6. The combination of stabilized ammonium with a range of consortium products based on T. harzianum OMG16, B. amyloliquefaciens, micronutrients, and humic acids completely compensated the effect of a TSP fertilization on field establishment, nutrient acquisition, and yield formation in maize, while non-stabilized urea-di-ammonium phosphate fertilization was largely ineffective. These findings suggest that the efficiency of PSM-plant interactions can be influenced by the form of N fertilization, offering promising perspectives for synergistic effects with stabilized ammonium fertilizers.
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On-farm land management strategies and production challenges in United States organic agricultural systems
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Authors: Isaac Kwadwo Mpanga, Russell Tronstad, Jessica Guo, David Shaner LeBauer, Omololu John Idowu
Abstract
The need to reduce the negative impacts of agriculture on the environment and the consumer demands for food produced without synthetic chemical inputs have led to organic agriculture production systems. The United States (US) commands about half of the market share of organic products worldwide and is home to half of the world's organic farmers, but limited information is available on trends of on-farm land-use practices and challenges in organic crop production systems. This study utilizes the agricultural production surveys from the United States Department of Agriculture (USDA) from 2008 to 2019 to investigate state and national trends in organic farm area, number, and sales, and to evaluate national trends in on-farm land-use practices and challenges facing US organic production. From 2008 to 2019, the number of certified organic farms, land area, and sales increased by 5, 6, and 12%, respectively. The use of green and animal manures is the most common land-use practice in certified organic crop production systems. The number of farms using the on-farm organic practices remained the same or increased steadly except organic mulch/compost which declined. However, all the practices declined proportionally, except rotational grazing which recorded an increase in 2019. The most significant primary challenges faced by certified organic farmers are related to regulations of organic practices and production costs which worsen over time. United States certified organic production has the potential for expansion in terms of farm numbers, land area, markets, and increased adoption of regenerative agricultural practices. However, for this to occur, efforts involving farm-level research and policy reviews with direct farmer involvement are needed to address these primary challenges facing organic farmers.
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More info: https://doi.org/10.1016/j.crsust.2021.100097
Grape pomace’s potential on semi-arid soil health enhances performance of maize, wheat, and grape crops
Authors: Isaac K. Mpanga, Günter Neumann, Judith K. Brown, Joseph Blankinship, Russell Tronstad, Omololu Idowu.
Abstract
Background: Grape pomace (GP) is a by-product of wineries after filtering the grape juice for wine production. GP contains seeds, pulp, skin, and stalks with acidic properties, and it is normally composted before using as a soil amendment. However, composting GP requires more time, labor, and equipment; furthermore, composting loses some of the desirable organic acids for arid soils. The acidic properties of these organic acids and the
plant nutrients in GP make it a desirable amendment for arid soils in both non-composted
and composted forms.
Aim: This study investigates the potential of directly applying GP as a soil amendment and
its impact on arid soil health and plant performance.
Methods: To test the potential of non-composted GP as a soil amendment, greenhouse and field studies were conducted by combining GP with existing management practices (manure application for soil used in the greenhouse study and fertigation for the field study) to assess the effects of GP on soil health and crop (maize, wheat, and grape)
performance.
Results: Adding 5% GP to an alkaline soil significantly increased maize and wheat growth and shoot nutrient concentrations in the greenhouse and grapes in the field (48% yield increase). The significance of GP on maize, wheat, and grapes was associated with soil nutrient enhancements (i.e., nutrients supplied, increase in organic matter and microbial biomass increase, reduction in pH, and better nutrient mobilization).
Conclusion: GP has the potential for direct use as a soil amendment for soil and
crop health improvement, especially in arid soils with high pH and limited soil organic matter.
​More information: https://onlinelibrary.wiley.com/doi/10.1002/jpln.202200232
Adaptation of resilient regenerative agricultural practices by small-scale growers towards sustainable food production in north-central Arizona
Isaac K. Mpanga, Ursula K. Schuch, Jeff Schalau
Abstract
The demand for agricultural lands for other uses because of population growth and extreme climate in Arizona led to 57% decrease in average farm size and 127% increase in farm numbers from 1997 to 2017, which threaten sustainable local food production. Small-scale family farms of less than 10 acres make up 50% of the farmer population in the state and have a vital role in resilient and sustainable practices that maximize land use with less negative impact on the environment. This study investigated land use and farm practices among small-scale growers in north-central Arizona in their resilience in sustainable food production. The finding revealed 52% of the small farms are family operations with dominant regenerative and sustainable practices (27% cover cropping, 26% compost, 23% crop rotation, 22% animal and green manure, 21% no-till, and 18% reduced tillage) with less interest in conventional practices (5% intensive tillage and 13% synthetic fertilizers). Ninety-five percent of the growers used biological, cultural, or mechanical practices for weed, pest, and disease control, while only 5% used conventional synthetic chemicals. For water use, 78% of the growers used water-saving irrigation practices (drip, subsurface, and sprinklers), while 11% used open flood irrigation. Driving forces for the sustainable practices among the small-scale growers are their consumers (community supported agriculture, restaurants, Farmers' Markets, and farm stands) and extreme climate conditions. Small-scale growers have great potential in advancing resilient, environmentally friendly practices for sustainable local food production and environmental stewardship.
Original languageEnglish (US)
Article number100067
JournalCurrent Research in Environmental Sustainability
Volume3
StatePublished - Jan 2021
Soil Health Assessment of Three Semi-Arid Soil Textures in an Arizona Vineyard Irrigated with Reclaimed Municipal Water
Authors: Isaac K. Mpanga, Herbert Sserunkuma, Russell Tronstad, Michael Pierce, and Judith K. Brown
Abstract
The depletion of freshwater supply is occurring at a faster rate than it is being replenished. The agriculture sector is the largest consumer of freshwater for irrigation and production-related processes. The use of reclaimed municipal water for the irrigation of crops offers a sustainable alternative solution for reducing the dependence of agriculture on freshwater. However, the long-term and continuous use of reclaimed water may contribute to soil salinity and sodicity limitations in agriculture production. The chemical and microbial properties of three different soil textures (all Alluvial soil with 60% clay: pH 8.6; 30% clay: pH 8.2; and 20% clay: pH 7.9) were evaluated in a vineyard irrigated using reclaimed water (126 mg/L Na+, 154 mg/L Cl−, 7.6 water pH, and 1.2 dS/m ECw). The results indicate that the reclaimed irrigation water significantly (p < 0.05) increased the pH (by 0.4 to 18%), nitrate-N (over 100%), electrical conductivity (EC) (over 100%), and sodium absorption ratio (SAR) in these arid soils. A significant decline in microbial respiration (48 to 80%) was also documented in the three different soil textures that received reclaimed water. Although using reclaimed water for crop irrigation may be a substitute for using limited freshwater resources and offer a partial solution to increasing water security for wine grape production, the development of innovative technologies is needed for the long-term use of reclaimed water to counter its undesirable effects on soil quality.
Soil Type-Dependent Interactions of P-Solubilizing Microorganisms with Organic and Inorganic Fertilizers Mediate Plant Growth Promotion in Tomato
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Authors: Isaac Kwadwo Mpanga, Harrison Kwame Dapaah, Joerg
Geistlinger, Uwe Ludewig, Günter Neumann
Abstract
The use of plant growth-promoting microorganisms (PGPMs) as bio-effectors (BEs) to improve the nutrient acquisition of crops has a long history. However, limited reproducibility of the expected effects still remains a major challenge for practical applications. Based on the hypothesis that the expression of PGPM effects depends on soil type and the properties of the applied fertilizers, in this study, the performance of selected microbial inoculants was investigated for two contrasting low-fertility soils supplied with different organic and inorganic fertilizers. Greenhouse experiments were conducted with tomato on an alkaline sandy loam of pH 7.8 and an acidic loamy sand of pH 5.6 with limited phosphate (P) availability. Municipal waste compost, with and without poultry manure (PM), rock phosphate (RP), stabilized ammonium, and mineral nitrogen, phosphorus and potassium (NPK) fertilization were tested as fertilizer variants. Selected strains of Bacillus amyloliquefaciens (Priest et al. 1987) Borriss et al. 2011 (FZB42) and Trichoderma harzianum Rifai (OMG16) with proven plant growth-promoting potential were used as inoculants. On both soils, P was identified as a major limiting nutrient. Microbial inoculation selectively increased the P utilization in the PM-compost variants by 116% and 56% on the alkaline and acidic soil, while RP utilization was increased by 24%. This was associated with significantly increased shoot biomass production by 37–42%. Plant growth promotion coincided with a corresponding stimulation of root growth, suggesting improved spatial acquisition of soluble soil P fractions, associated also with improved acquisition of nitrogen (N), potassium (K), magnesium (Mg), and calcium (Ca). There was no indication for mobilization of sparingly soluble Ca phosphates via rhizosphere acidification on the alkaline soil, and only mineral NPK fertilization reached a sufficient P status and maximum biomass production. However, on the moderately acidic soil, FZB42 significantly stimulated plant growth of the variants supplied with Ca–P in the form of RP + stabilized ammonium and PM compost, which was equivalent to NPK fertilization; however, the P nutritional status was sufficient only in the RP and NPK variants. The results suggest that successful application of microbial biofertilizers requires more targeted application strategies, considering the soil properties and compatible fertilizer combinations.
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More info: https://www.mdpi.com/2073-4395/8/10/213#
