Global food security is a worldwide concern. Food insecurity is a significant threat to poverty and hunger eradication goals. Agriculture is one of the focal points in the global policy agenda. Increases in agricultural productivity through the incorporation of technological advances or expansion of cultivable land areas have been pushed forward. However, production growth has slowed in many parts of the world due to various endemic challenges, such as decreased investment in agricultural research, lack of infrastructure in rural areas, and increasing water scarcity. Climate change adversities in agriculture and food security are increasing. Recently, the COVID-19 pandemic has severely affected global food supply chains. Economic and social instability from the pandemic contribute to long-term disturbances. Additionally, conflicts such as war directly affect agriculture by environmental degradation, violence, and breaches of national and international trade agreements. A combination of food security and climate change challenges along with increased conflicts among nations and post-COVID-19 social and economic issues bring bigger and more serious threats to agriculture. This necessitates the strategic design of policies through multifaceted fields regarding food systems. In this comprehensive review, we explore how these three challenging factors, COVID-19, climate change, and conflicts, are interrelated, and how they affect food security. We discuss the impact of these issues on the agricultural sector, plus possible ways of preventing or overcoming such adverse effects.

Anaerobic digestion and digestate solid–liquid separation are manure treatment strategies used on commercial dairy farms. These treatment strategies typically result in increased total ammoniacal nitrogen (TAN) concentration and pH, and reduced dry matter content, which tend to increase ammonia (NH₃) emissions following field application. We hypothesized that shallow‐disk injection of liquid‐separated, anaerobically digested dairy manures, compared to surface application without incorporation on no‐till farmland, would reduce NH₃‐N emissions and conserve manure‐N for crop production. Six corn (Zea mays L.) silage studies were established on commercial dairy farms across Pennsylvania in 2021–2023 with side‐by‐side field‐scale treatment comparison strips replicated five times per farm. We quantified the impact of liquid‐separated, anaerobically digested manure application methods on (i) NH₃ emissions for 24 h after application, (ii) in‐season soil nitrate‐N, (iii) cornstalk nitrate at harvest, (iv) corn silage production, and (v) returns on investment. Surface‐applied liquid digestate lost twice as much NH₃ as injected digestate during the first 6 h after application and 58% more cumulative NH₃ loss over 24 h after application. Pre‐sidedress soil nitrate‐N test and corn stalk nitrate at harvest indicated there was more than sufficient N for corn with both treatments. Across farms, corn silage yield was 3.8% greater (p < 0.05) with injection than surface broadcast and returns on investment were greater in five of the six comparisons. These findings indicate that injecting liquid‐separated anaerobically digested manure can reduce NH₃ loss, slightly increase corn silage yields and returns on investment, and offer environmental benefits by reducing harmful NH₃ emissions.

The pre‐sidedress soil nitrate test (PSNT) was developed over 30 years ago to determine sidedress nitrogen (N) fertilizer recommendations for corn (Zea mays L.). Since the original PSNT calibrations were developed, changes in production practices such as no‐till and cover cropping and increases in corn yields and N use efficiency could affect the accuracy of PSNT recommendations. To update the PSNT recommendations in Pennsylvania and demonstrate the test's efficacy, we compiled a dataset of 32 calibration sites and 13 demonstration sites where the PSNT was conducted, and the economically optimum N rate (EONR) for corn was determined from an N fertilizer yield response curve. We recalibrated the PSNT recommendation algorithm and compared its accuracy to the original calibration. The new calibration resulted in a single long‐term manure history factor that interacted with the PSNT result to adjust the sidedress N recommendation (−5.7 kg N ha⁻¹ [mg NO₃‐N kg⁻¹]⁻¹). The new calibration also included a term for a mixed species cover crop, which increased the sidedress N recommendation 56.2 kg N ha⁻¹. Finally, the coefficient that scales the N fertilizer recommendation based on yield goal decreased by 29% from the original calibration to 12.9 kg N Mg⁻¹ grain. The new algorithm for predicting EONR reduced the error of the sidedress N recommendation by one‐half compared to the original calibration. The new PSNT calibration will allow users to accurately determine sidedress N recommendations in sites with a long‐term manure history and underscores the importance of updating soil fertility recommendation algorithms with modern data.

Ammonia (NH₃) loss following manure application is an environmental concern and N loss for crop production. Manure injection typically reduces NH₃ loss compared to surface application without incorporation but increases emissions of nitrous oxide (N₂O), which is a potent greenhouse gas. Synchronizing manure in spring with cover crop (CC) growth may increase N recovery and reduce N₂O emissions compared to applying manure later in the absence of growing crops. We compared the two following manure application methods: shallow‐disk injection (IM) or surface banding without incorporation (BM) to annual ryegrass (Lolium multiflorum L.) and red clover (Trifolium pratense L.) CC at two times: early spring on growing CC (EARLY) and late spring on terminated CC (LATE). The randomized split‐plot block experiment was conducted at Rock Springs, PA, during 2021–2022. After manure application, we measured NH₃ for 72 h and N₂O throughout the growing season. Aboveground CC biomass, N, and C:N ratio; pre‐sidedress soil nitrate; corn (Zea mays L.) stalk nitrate; and silage yield were assessed. Averaged across application times, compared to BM, IM reduced cumulative NH₃ loss, increased soil N, and resulted in 13% greater corn yield but increased yield‐scaled N₂O. Compared to BM LATE, BM EARLY reduced NH₃ loss by 43%, increased CC N, reduced N₂O emission by 50%, but decreased corn yield by 11%. When IM was EARLY compared to LATE, CC N increased 84%, cumulative N₂O loss decreased 55%, and corn yield was similar. Injecting manure to growing CCs offers a strategy for reducing detrimental NH₃ and N₂O emissions and maintaining corn yield.

Biotic interaction of cover crops (CCs) can have a legacy effect on succeeding crops mediated by changes in nutrient dynamics. Depending on species, CCs influence nitrogen (N) dynamics by sequestering N and subsequent N release. Interactions of three CC species, Austrian Pea (Pisum sativum L.), winter rye (Secale cereal L.), and winter camelina (Camelina sativa L.), and three different soils were studied under greenhouse conditions on wheat (Triticum aestivum L.) grain yield and soil N availability. CCs were grown for two months and then incorporated, followed by the planting of wheat. CC biomass production ranged from 0.10 to 2.05 Mg ha⁻¹ in this order by species: Pea> Rye> Camelina. Biomass production by soil was in the order of Casselton>Ada>Minot. Succeeding wheat grain yield and grain N uptake was highest under pea in the order of pea>camelina>control>rye. Rye reduced grain yield and N uptake. Wheat yield ranged from 2.19 to 3.24 Mg ha⁻¹ depending on CC species-soil interaction. The N balance showed a 3–79% higher N surplus with the CCs. The N balance ranged from 78 kg N ha⁻¹ for the control to 140 kg N ha⁻¹ for pea. N surplus was greater for a pea in all soils, indicating pea can be regarded as an effective cover that can efficiently recycle N and provide additional agronomic benefits. Greater N balance with CCs shows that CCs can increase the amount of N accounted for in the system, which can significantly affect the N dynamics throughout the growing season.