Agricultural Soil Science in a Changing Climate: Soil Health, Carbon Cycling, Nutrient Dynamics and Agroecosystem Resilience

Rising mean temperatures, more frequent extremes and the progressive salinisation of agricultural land are eroding the productivity gains on which global food supply depends. Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated (Cas) technologies are widely presented as a means of building abiotic stress tolerance directly into elite germplasm, yet the literature has expanded far faster than the evidence base that would justify confidence in field-scale benefit. This review critically evaluates that literature. It examines how the editing toolbox has moved from simple gene disruption towards allelic series, regulatory-region modification and transcriptional or epigenetic modulation, and asks what each modality can realistically deliver for quantitative stress traits. Evidence is then appraised by stress domain, covering water deficit, salinity and ionic imbalance, high and low temperature, oxygen deficiency and soil chemical constraints. Recurring problems are identified rather than catalogued: a heavy dependence on glasshouse or pot-based phenotyping under severe, abrupt stress; asymmetric reporting in which yield under non-stressed conditions is frequently omitted; near-exclusive reliance on a small number of model cultivars; and limited attention to combined or sequential stresses. Stomatal density engineering is treated as an instructive case in which mechanistically attractive interventions have produced inconsistent and sometimes opposing outcomes across species and growth environments. The strongest evidence supports interventions that tune expression of a native locus in a stress-responsive manner rather than eliminating gene function outright, and that have been evaluated under field conditions with an explicit accounting of yield potential. Persistent constraints include genotype-dependent regeneration, incomplete transferability of targets between species, divergent regulatory treatment across jurisdictions, and an evidence base geographically concentrated in a few research systems. Priorities are proposed for multi-environment field evaluation, standardised stress reporting, and the extension of editing capability to crops and regions currently underserved.