Descriptive statistics
The descriptive statistics presented in Table 1 shows MPL and MPK in both main and coarse cereals, along with annual temperature and rainfall, gives important understandings into how these factors interact under varying climatic conditions in India. The results reveal a marked divergence in input productivity between cereal categories and highlight the vulnerability of coarse cereals to climate variability.
In the case of main cereals, the MPL demonstrates substantial efficiency, with a mean value of 76.50 in the overall period and peaking at 106.71 during favourable years. However, it drops precipitously to 0.03 during stress periods, indicating that land productivity in main cereals is highly sensitive to climate fluctuations. The considerable standard deviation, especially under favourable conditions (278.67), suggests regional and temporal variability in land use efficiency. The skewness statistics reinforce this, showing a leftward skew during stressful periods, implying that most years yield below-average returns on land under climate stress.
The MPK in main cereals follows a more stable pattern. The mean MPKMC remains relatively high in both the overall (5.51) and favourable periods (5.29), with a notable decline in stressful years (0.86). While still impacted by climatic conditions, the smaller relative drop compared to MPLMC suggests that capital investments in main cereals may retain some productivity even during adverse periods-likely a result of greater capital deepening, irrigation infrastructure and policy support. The skewness is positive across all periods, indicating the presence of a few high-performing years, likely driven by technological advancements or favourable policy conditions.
In contrast, coarse cereals show consistently lower and more climate-sensitive productivity outcomes. The MPL in coarse cereals averages -0.75 in the overall period, with a moderate improvement during favourable years (0.54), but becomes strongly negative during stress conditions (-5.55). This pattern reflects the structural vulnerabilities of coarse cereals, which are typically cultivated in rainfed and resource-poor settings.
The MPKCC mirrors this sensitivity, with an overall mean of 0.44, dropping to -2.59 in stressful years. Even during favourable conditions, capital productivity remains marginal (-0.18), suggesting that returns on capital in coarse cereal production are persistently low and highly susceptible to climate shocks. The data underline a critical point: capital and land inputs in coarse cereal cultivation are not only underutilized but also poorly buffered against climatic variability, unlike main cereals
The climate variables further contextualize these patterns. While temperature remains relatively stable across all periods (~25.5
oC), rainfall exhibits considerable fluctuation-with the lowest mean rainfall recorded during stress periods. This validates the construction of the CI and supports its explanatory power in understanding productivity shifts.
The data confirm a structural disparity between main and coarse cereals. While main cereals benefit from robust input productivity and resilience under varying climatic conditions, coarse cereals remain highly vulnerable.
Inferential statistics
The regression analysis from Model I in Table 2 reveals a consistently strong and statistically significant positive relationship between the marginal productivity of capital in main cereal and that in coarse cereals. This suggests that improvements in capital productivity within main cereals are closely associated with corresponding gains in coarse cereals, pointing to systemic interdependence and possible spillover effects in input use and efficiency across cereal categories.
The climate index, constructed as a differential standardized measure of temperature and rainfall, shows a negative and marginally significant impact on capital productivity in coarse cereals. This indicates that greater climatic stress-marked by above-normal temperatures and below-normal rainfall-tends to suppress productivity, albeit modestly in the overall sample. The model demonstrates a moderate explanatory power, accounting for approximately 43% of the variance in the marginal productivity of capital in coarse cereals and reflects a reasonably well-specified structural relationship.
When the analysis is segmented based on climatic conditions, further nuances emerge. During stress years (CI < 0.5), the influence of marginal productivity of capital in main cereals on marginal productivity of coarse cereals remains positive and statistically significant, though the magnitude is smaller. Importantly, the climate index exerts a more pronounced negative effect (-0.507) in this subsample, underlining that capital productivity in coarse cereals is particularly vulnerable to adverse climate conditions. Notably, the model’s explanatory power increases to 52%, suggesting that linkages between capital productivity in cereal systems become more structurally evident when external stressors are high.
Conversely, in favourable years (CI > 0.5), the capital productivity relationship strengthens substantially, with a much larger coefficient (2.295), reinforcing the idea of strong complementarity and synergy in capital allocation and effectiveness between cereal types under benign conditions. However, the climate index becomes statistically insignificant in this context, implying that when weather conditions are favourable, climate does not impose significant constraints on capital productivity in coarse cereals. This asymmetry in climate influence across regimes underscores the critical role of environmental stability in moderating or amplifying productivity responses.
The empirical findings from Model II in Table 3 pertaining to the marginal productivity of land in coarse cereals offer valuable insights into the structural dynamics within the cereal economy. A statistically significant negative association between capital productivity in main cereals and capital productivity in coarse cereals suggests a potential resource allocation trade-off. This pattern indicates that increases in capital productivity within main cereals driven by mechanization, irrigation infrastructure, or input intensification are occurring at the expense of land productivity in coarse cereals.
The climate index, derived as a composite of stand-ardized temperature and rainfall deviations, registers a negative but statistically insignificant coefficient in the full sample model. This outcome suggests that, while climatic variability is intuitively important for agricultural productivity, its direct linear effect on land productivity in coarse cereals may be limited or mediated through other interacting variables. Moreover, the relatively low R-squared value indicates a weak model fit, implying that land productivity is likely influenced by a broader set of unobserved or localized factors.
When the sample is disaggregated by climatic regimes, further complexity emerges. During stress years (CI < 0.5), the influence of land productivity of main cereals on land productivity of coarse cereals becomes statistically insignificant and only the climate index shows a marginal effect. This finding suggests that in climatically adverse conditions, land productivity in coarse cereals is less responsive to capital dynamics in other cereal groups and more likely contingent on micro-climatic conditions, crop-specific resilience traits and farmer adaptation strategies. The model’s explanatory power also declines in this subsample, reinforcing the notion that land productivity during climatic stress is shaped by highly localized, non-systemic variables.
In contrast, during favourable climatic conditions (CI > 0.5), the negative relationship between capital productivity of main cereals and capital productivity of coarse cereals becomes stronger and statistically significant, pointing to the re-emergence of competitive dynamics in input use. It is plausible that in the absence of climate-induced constraints, systemic biases in investment and input delivery become more distinct, favouring main cereals over coarse cereals. Notably, the climate index remains statistically insignificant in this regime, suggesting that favourable weather conditions may neutralize direct climatic constraints, thereby amplifying the role of structural and institutional factors in influencing land productivity.