The research team, led by Nistha Khanna of Mizoram University together with colleagues from Nagaland University and O.P. Jindal Global University, sampled soils from six agricultural sites spread across six of Lucknow district’s eight administrative blocks between 2023 and 2025. Sampling was conducted three times each year: in April and May before the monsoon, in June and July during the monsoon itself, and in October and November after the rains had passed. At each site, soils were drawn from two depths, 0 to 15 centimeters and 15 to 30 centimeters, using a soil corer, then brought to the laboratory for analysis using long-established techniques, including the Walkley and Black titration for organic carbon and the Bray and Kurtz extraction for available phosphorus.

The region receives an average of 896 millimeters of rainfall annually, almost all of it delivered by the southwest monsoon between June and October. This single hydrological pulse, the researchers hypothesized, would leave a measurable fingerprint on nearly every property of the soil. Their hypothesis was largely confirmed. Textures shifted across seasons: pre-monsoon samples mixed sandy clay loam, clay loam, and loam, while monsoon samples were dominated by clay loam and loam, and post-monsoon samples leaned toward sandy clay loam and sandy clay. On average, the soils contained about 45 percent sand, 30 percent clay, and 25 percent silt.

Statistical analysis using linear mixed models revealed that the seasonal signal was strongest for the coarse and fine mineral fractions themselves. Sand content varied dramatically with season, and clay content did likewise, both with p-values below 0.001, an indication that the monsoon physically redistributes particles through percolation and structural change. Soil organic carbon and organic matter also fluctuated strongly across seasons, peaking in the pre-monsoon and post-monsoon periods and dipping during the rains. Soil moisture content and available potassium likewise changed significantly from season to season, while soil pH, bulk density, available nitrogen, available phosphorus, water-holding capacity, and silt content remained comparatively stable.

The measured nutrient levels told a generally encouraging story. Available nitrogen was high across all sites, ranging from 102.23 to 396.08 kilograms per hectare, with the highest value recorded at Site S5 in the surface layer after the monsoon, a pattern the authors attribute to enhanced microbial mineralization of organic matter once the rains replenish soil moisture. Available potassium ranged from 125 to 300 kilograms per hectare and tended to be slightly higher after the monsoon, while available phosphorus spanned 7.53 to 34.3 kilograms per hectare. Soil pH remained in a near-ideal window for nutrient uptake, between 6.5 and 8.12, and average soil organic carbon stood at about 2.5 percent, a level many degraded Indo-Gangetic soils no longer reach.

Correlation analysis added texture to the picture. Soil organic carbon correlated positively with sand content and negatively with clay, suggesting that the coarser soils in the study area may accumulate organic matter more readily, perhaps because better aeration and drainage support microbial litter processing. Phosphorus and potassium moved together closely, hinting at shared geochemical controls, while the negative relationship between silt and pH pointed to subtle acidification tendencies in finer sediments.

To distill this tangle of interacting variables, the team employed principal component analysis, a multivariate technique that compresses correlated measurements into a few independent axes of variation. The first three components accounted for the largest shares of the dataset’s variance, at 29.6, 20.7, and 11.9 percent respectively, and the first five components together explained 79.3 percent. The dominant gradient, the first component, contrasted clay-dominated soils with sandy, organic-rich ones, while the second captured a nutrient-moisture axis that separated fertile, wet soils from comparatively depleted ones. In plain terms, the fate of a Lucknow field is governed first by its texture and organic matter, and second by how water and nutrients travel through it.

Why does this matter beyond the district boundary? The rice-wheat-mustard rotation that dominates Lucknow’s farmland extracts nutrients continuously throughout the year, and flooded rice cultivation alters soil redox chemistry in ways that reshape nitrogen and phosphorus dynamics. Continuous fertilizer application without soil testing, the authors note, frequently produces nutrient imbalances, declining organic carbon, and wasteful nutrient use. By mapping how fertility indicators swing with the seasons, the study gives farmers and policymakers a timing framework: post-monsoon mineralization offers a natural nitrogen flush, potassium availability improves after the rains, and organic carbon conservation efforts are best judged against seasonal baselines rather than single snapshots.

The study is not without limits. The authors acknowledge that environmental drivers such as rainfall intensity and microbial activity, which likely mediate many of the observed seasonal shifts, were not directly measured. Nor does the two-year window capture longer climatic oscillations. Still, by combining principal component analysis with linear mixed models, a methodological pairing rarely applied to seasonal soil data in this district, the work provides something previous single-season surveys could not: a statistically grounded picture of soil as a living, breathing system that inhales with the monsoon and exhales through the dry months. The researchers suggest that season-sensitive management, periodic organic inputs, moisture conservation, and balanced nutrition, will be essential to keeping these soils productive for generations to come.

For the farmers of Lucknow district, whose average land holdings are barely 0.8 hectares, the message is both practical and hopeful. Their soils, the study concludes, retain a moderate to good fertility and a strong capacity for long-term management. The monsoon that floods their paddies and sows their wheat is the same force that reorganizes their soil each year, and understanding that rhythm may prove to be one of the cheapest tools available for sustaining the harvest.

Subject of Research: Seasonal variation in the physicochemical properties of agricultural soils in Lucknow district, Uttar Pradesh, India

Article Title: Seasonal variation in physicochemical properties of some agricultural soils in Lucknow district, Uttar Pradesh of India

Article References: Khanna, N., Lalruatkimi, C., Devi, K. B., Adam, A. A., Yam, G., & Tripathi, O. P. (2026). Seasonal variation in physicochemical properties of some agricultural soils in Lucknow district, Uttar Pradesh of India. Discover Soil, 3(1), Article 147. https://doi.org/10.1007/s44378-026-00302-0

Image Credits: AI Generated

DOI: 10.1007/s44378-026-00302-0

Keywords: soil science, Indo-Gangetic Plain, seasonal variation, soil fertility, soil organic carbon, monsoon, principal component analysis, linear mixed models, sustainable agriculture, Uttar Pradesh, nutrient management, soil texture

The team assembled multi-decadal records for eight major crops: rice, wheat, maize, barley, millet, potato, sugarcane, and pulses. Crop production data spanned 1991 to 2021, drawn from the Jila Sankhyikiya Patrika and official records of the Uttar Pradesh Directorate of Economics and Statistics, while cropping-area data covered 1991 to 2015. Annual rainfall figures came from the India Meteorological Department. By combining these datasets with Pearson correlation analysis, Mann-Kendall trend testing, Sen’s slope estimation, and published crop-specific water footprint values, the researchers built a statistical portrait of an agricultural system in transition. Crucially, they were careful to frame their findings as statistically supported associations rather than proof of causation, a distinction that lends the work its scientific discipline.

The headline result is stark. Barley production in the district fell by approximately 74 percent between 1991 and 2021, sugarcane production dropped by about 41 percent, and pulses declined by roughly 60 percent. The corresponding cultivated areas shrank even more dramatically over 1991 to 2015, with barley losing about 80 percent of its area, sugarcane 48 percent, and pulses 71 percent. Meanwhile, rice, potato, and millet surged in the opposite direction. Rice production climbed by an extraordinary 1218 percent, potato by 829 percent, and millet by 138 percent, while their respective cropping areas expanded by 766, 405, and 71 percent. These are not marginal adjustments but a wholesale reordering of the district’s agricultural economy.

Yield analysis for the common period 1991 to 2015 added a second layer of nuance. Wheat production rose even as its cultivated area declined, but this was achieved against a falling yield, which slipped from 2.81 to 2.32 tonnes per hectare, a decline of 17.67 percent. Maize told the opposite story, with yields jumping 133.69 percent from 0.94 to 2.18 tonnes per hectare. Potato yields increased by 58.38 percent, millet by 16.81 percent, and rice by 36.72 percent, while barley, sugarcane, and pulses all recorded yield losses, with pulses suffering a striking 64.75 percent decline. The researchers conclude that both cultivated area and productivity contributed to changing production, though their relative importance varied considerably from crop to crop.

The hydrological backdrop to these shifts is subtle rather than dramatic. Annual rainfall in Aligarh District showed a weak declining tendency over the study period, with the Mann-Kendall test yielding a negative but statistically non-significant trend (Z = -1.14, p = 0.254). Sen’s slope estimated an average decline of 4.66 millimetres per year, while linear regression produced a nearly identical negative slope of 4.60 millimetres per year, with a coefficient of determination of just 0.056. In plain terms, rainfall has drifted downward without a statistically significant trend, meaning the study cannot claim a decisive drying of the district. Yet even a modest, persistent downward pressure on water availability can matter enormously in a region where agriculture consumes the bulk of freshwater resources.

The most compelling technical finding lies in the correlation structure. The researchers found that the eight crops segregated into two coherent groups with strong inverse relationships. Rice, potato, and millet moved together in tight positive correlation, with rice production correlating at roughly 0.96 with potato and 0.87 with millet. The second group, comprising wheat, barley, sugarcane, maize, and pulses, moved in the opposite direction, with rice production correlating at approximately -0.88 with barley and -0.55 with sugarcane. The same pattern held for cropping area, where rice tracked potato at about 0.95 and barley at -0.87. This coordinated dance indicates systematic, district-wide crop substitution rather than a collection of isolated farm-level decisions, and the consistency across two independent datasets strengthens the inference considerably.

To interpret these patterns hydrologically, the authors turned to published green water and blue water footprint values, where green water denotes rainfall-derived soil moisture and blue water denotes irrigation drawn from surface water and groundwater. Agriculture accounts for roughly 70 to 85 percent of global freshwater withdrawals and nearly 85 percent of groundwater extraction worldwide, making these categories central to sustainability debates. Rice, despite its reputation as water-intensive, draws most of its requirement from monsoon green water, with a published footprint of about 2040 cubic metres per tonne of green water against roughly 937 cubic metres per tonne of blue water. Potato carries a very small blue water footprint of only about 28 cubic metres per tonne, with a green water component near 244 cubic metres per tonne. Millet, similarly, depends overwhelmingly on rainfall rather than irrigation. In contrast, sugarcane, with a green water footprint near 1107 and a blue water footprint near 455 cubic metres per tonne, demands a continuous water supply throughout the year.

Viewed through this lens, the district’s crop shifts take on a coherent shape. The crops that expanded, rice, potato, and millet, are either aligned with the monsoon season or have short growing durations and low year-round irrigation requirements. The crops that contracted, barley, sugarcane, and pulses, carry prolonged water demands and comparatively higher published blue water footprints. The researchers are careful to stress that these footprint values are generalized literature estimates, not field measurements specific to Aligarh, and serve only as interpretive context. They likewise caution that many non-hydrological forces, including market prices, minimum support price arrangements, subsidies, irrigation infrastructure, mechanization, improved varieties, and farmer preferences, could influence crop choice and were not directly analysed. The observed shifts, in other words, are statistically associated with water availability and hydroclimatic variability, but water is not proven to be the sole or even primary driver.

The study’s practical implications are nonetheless significant for a district that sits atop the Ganga-Yamuna Doab, one of India’s most productive alluvial aquifer systems, bounded by the Ganga and Yamuna rivers and sustained by a subtropical monsoon climate delivering roughly 800 to 900 millimetres of rain annually. The authors recommend artificial groundwater recharge and rainwater harvesting at suitable locations, systematic monitoring of groundwater levels and extraction, irrigation scheduling keyed to crop growth stages, and adoption of water-saving technologies such as drip and sprinkler systems where feasible. Crop diversification toward lower-irrigation options is also suggested for water-constrained areas. The work is not without limitations: cropping-area data were unavailable beyond 2015, groundwater-level and extraction records were not available in a consistent format, and the Pearson correlation framework identifies association rather than causation. Even so, by documenting statistically robust, two-decade-long crop-water alignments at the district scale, the research provides a template for agricultural planning across the wider Indo-Gangetic Plain, where millions of farming households face the same slow squeeze on water that Aligarh’s changing fields now reveal.

The green water and blue water framework used in the study originates from water footprint accounting, a method developed to trace how crops consume rainfall versus irrigation water across their growing cycles. Because green water cannot be diverted or stored at scale, crops that depend on it are effectively tethered to the timing and reliability of the monsoon, while blue water dependence translates directly into pressure on aquifers and surface sources. This distinction matters in the Ganga-Yamuna Doab, where decades of intensive groundwater irrigation have made aquifer depletion a persistent regional concern, and where recharge is governed by the same precipitation patterns that appear to be drifting downward in Aligarh.

The crop substitutions documented in the district also carry nutritional implications. Pulses are a principal source of dietary protein in much of northern India, and their roughly 60 percent decline in production over three decades suggests that local food systems may be trading protein-rich legumes for starch-heavy staples such as rice and potato. Similar transitions have been observed elsewhere in South Asia, where water-intensive cereals have expanded at the expense of coarse grains and legumes, reshaping both agricultural landscapes and diets. The authors note that such crop substitution can alter dietary diversity and nutrient availability within local food systems, and can also influence market prices, affecting affordability for consumers beyond the farming community itself.

Methodologically, the study fills a notable gap. District-scale assessments that jointly examine long-term precipitation records, production statistics, cultivated area, and crop-specific water footprints remain rare for the Indo-Gangetic Plain, despite the region’s centrality to India’s food security. By evaluating eight crops simultaneously within a common statistical framework, the analysis offers a replicable template that other districts could adopt using the same government statistical publications. The authors also emphasize that irrigation itself can influence regional atmospheric processes and precipitation dynamics, creating feedbacks between agricultural practice and climate, a reminder that cropping choices in one district may ripple outward into the broader hydrological system.

Subject of Research: Long-term associations between changing water availability and agricultural crop shifts in Aligarh District, Uttar Pradesh

Article Title: Agricultural crop shifts associated with changing water availability in Aligarh District, Uttar Pradesh

Article References: Singh, D. S., & Gupta, T. P. (2026). Agricultural crop shifts associated with changing water availability in Aligarh District, Uttar Pradesh. Discover Geoscience, 4(1), Article 351. https://doi.org/10.1007/s44288-026-00721-0

Image Credits: AI Generated

DOI: 10.1007/s44288-026-00721-0

Keywords: green water, blue water, water footprint, crop pattern change, Indo-Gangetic Plain, groundwater dependence, hydroclimatic variability, Aligarh District, Uttar Pradesh, rice, sugarcane, sustainable agriculture