Rice-wheat cropping system (RWCS), a lifeline for the majority of the population in South Asia is under stress, due to the imbalanced and indiscriminate use of fertilizers. Therefore, we conducted an on-farm study at eight locations (Amritsar, Katni, Nainital, Samba, Pakur, Kanpur, Ambedkarnagar, and Dindori) covering five agro climatic zones of six Indian states (Jammu and Kashmir, Punjab, Uttarakhand, Uttar Pradesh, Madhya Pradesh, and Jharkhand) to (i) calculate the partial factor productivity (PFP) and agronomic use efficiency (AUE) to judge the response of NPK and Zn on grain yield of rice and wheat in RWCS and (ii) to work out the economic feasibility of different combinations of NPK in rice and wheat. Seven fertilizer treatments: Control (0-0-0), N alone (N-0-0), NP (N-P-0), NK (N-0-K), NPK (N-P-K), NPK+Zn (N-P-K-Zn), and FFMP (Farmers Fertilizer Management Practice) were assigned to all the locations. The levels of applied nutrients were used as per the standard recommendation of the location. The average of all the locations showed that the use of NP enhances the grain yield of rice and wheat by 105% and 97% over control, respectively. System productivity of RWCS was expressed in terms of rice grain equivalent yield (RGEY), Mg ha⁻¹. Among the locations, Samba recorded the lowest productivity of RWCS with fertilizer treatments. In contrast, the highest productivity of RWCS with fertilizer treatments was recorded at Amritsar, except with NPK and NPK+Zn fertilization, where Katni superseded the Amritsar. An approximately 3-fold productivity gain in RWCS was recorded with the conjoint use of NP over control across the locations. Overall, the results of our study showed that the balance application of NPK increased the productivity of RWCS 245% over control. Partial factor productivity of Nitrogen (PFP_n) N alone in rice varied across locations and ranged from 19 kg grain kg⁻¹ N at Pakur to 41 kg grain kg⁻¹ N at Amritsar. PFP_n of N alone in wheat also ranged from 15.5 kg grain kg⁻¹ of N at Ambedkarnagar to 28 kg grain kg⁻¹ N at Amritsar. However, across locations the mean value of PFP_n of N alone was 29 kg grain kg⁻¹ N in rice and 21 kg grain kg⁻¹ N in wheat. PFP_n increased when combined application of N and P sorted in both rice and wheat across the locations. Similarly, combined application of NPK increased partial factor productivity of applied phosphorus (PFP_p) in both the crops at all the locations. The combined application of NPK increased the PFP_k for applied K at all the location. The response of K application with N and P when averaged over the location was 114% in rice and 93% in wheat over the combined use of N and K. In our study, irrespective of fertilizer treatments, the agronomic use efficiency of applied N (AUE_n) and agronomic use efficiency of applied P (AUE_p) were greater in rice than in wheat across the location. With regards to the economics, the mean net monetary returns among the fertilizers treatments was minimum (INR 29.5 × 10³ ha⁻¹) for the application of N alone and maximum (INR 8.65 × 10³ ha⁻¹) for application of NPK+Zn. The mean marginal returns across the locations was in order of N alone > NK > FFM > NPK > NP > NPK+Zn.

Erosion by water reduces soil quality and hence crop yield. Understanding the response of crop yields to soil erosion is vital in assessing agriculture’s vulnerability to erosion. However, these effects are difficult to quantify. The study presents a quantitative relationship between soil erosion and soil quality and productivity of rainfed wheat (Triticum aestivum) by comparing field plots with different degrees of erosion in some sub-tropical alfisols in the Doon Valley region of India. By comparing the topsoil depth with the reference site as the control, erosion severity was classified into different phases such as slight, moderate, severe, and very severe. A quantitative, weighted additive model was used to evaluate soil quality for different phases of erosion using soil clay content, water holding capacity, soil aggregate, soil organic carbon, pH, CEC, total N, available P, and available K. The synthesis of long-term experimental data revealed that the mean soil erosion rate varied from 5.5 Mg ha⁻¹ yr⁻¹ in slightly eroded plots to 33.4 Mg ha⁻¹ yr⁻¹ in very severely eroded plots. Compared with the reference forest, the soil organic carbon (SOC) declined by 81.4% and water holding capacity by 31% in severely eroded soils. A substantial loss of total N, extractable P, and available K was also observed. Water stable aggregates (WSA) decreased from 86% to 12.6%, and the cation exchange capacity (CEC) from 25 to 12.6 c mol⁽⁺⁾ kg⁻¹. The soil quality index was 0.7 in slightly eroded compared with 0.4 in severely eroded soil. Similarly, the sustainable yield index for wheat was 0.9 and 0.6 for slightly and severely eroded soils, respectively. Thus, there is a strong need to identify land management systems that reduce erosion risks, restore eroded soils, and enhance soil quality.