*3.2.3 Sustainable yield index (SYI) and green water use efficiency (WUE)*

The sustainability of crop production is measured by SYI. A high or low index indicates the level of variations in yield. It is measured as the standard deviations and it is seen as an indicator for sustainability. Nutrient management influences the long-term yield stability. Application of FYM plus mineral fertilizers increased SYI and WUE of the crop (**Figure 13**). WUE decreased by 67% without any fertilizer and by 40% at only FYM compared to the WUE of integrating FYM with NP fertilizer (**Figure 13**). A reduction of crop yield because of nutrient deficiency resulted in a low SYI and inefficient use of water.

### *3.2.4 Nutrient use efficiency*

Nitrogen use efficiency (NUE) was 73% at the integrated nutrition treatment (FYM + NP mineral fertilizer). Application of FYM only and FYM plus PK fertilizer decreased NUE to 49% and 51% (**Figure 14**). Low yield (**Figure 10**) due to low N availability in the FYM reduced NUE at the treatments FYM only and FYM plus PK fertilizer. The highest P use efficiency (PUE) of 66% was calculated at FYM + NK fertilizer (**Figure 14**). Low PUE of 51% at the application of only FYM and 32% at FYM plus PK fertilizer were recorded, because inadequate availability of N from FYM reduced yield (**Figure 10**) and P output. Combining FYM with NK or N fertilizer significantly increased PUE. K use efficiency (KUE) was increased to 99% at integrating FYM with NP fertilizer (**Figure 14**). It was decreased to 75% at the application of FYM only and decreased to 47% by omitting mineral nitrogen at FYM plus PK. The nitrogen deficiency in the FYM plus PK fertilizer treatment decreased yield and limited K recovery.
