Short-term (5 years) impact of tillage and residue management practices on physical properties and organic carbon (OC) of a silty clay soil was evaluated in a rice-wheat rotation in the Indo-Gangetic Plains of Bihar. The experiment had three conservation agriculture (CA) practices: one full (direct-seeded rice (DSR)-no-tilled wheat (NTW)-no-tilled mung bean (NTMB); fCA) and two partial (puddled transplanted rice (PTR)-NTW-conventionally tilled mung bean (CTMB); pCA1 and unpuddled transplanted rice (UPTPR)-conventionally tilled potato+maize (CTP + M)-NTMB; pCA2), which were evaluated against full conventional practice (puddled transplanted rice (PTR)-conventionally tilled wheat (CTW); TA). Subsurface compaction reduced and soil aggregation improved under both full and partial CA. Macro-and water-stable aggregates increased to a large extent (26 and 11%, respectively) in full CA and to a lesser extent in partial CA, mostly due to increase in coarse macroaggregate (2-8 mm) contents in the 0-10 and 10-20-cm depth soil layers. Steady-state infiltration rate nearly doubled under full CA, with larger pore volume recorded in 10-20 and 20-30-cm depth soil layers. The CA increased OC associated with all size fractions of aggregates in the surface soil layer (0-10 cm), but a higher amount of C was associated with macroaggregates, indicating relative stabilization of OC in the soil under CA. Change in bulk soil OC was larger in the 0-10-cm depth soil layer in favour of CA, which also had an 11% increase in OC stock in the 0-30-cm depth soil layer. Improvement in soil physical condition did not effectively translate into increased rice or wheat yields, but the system productivity increased largely. Highlights • Conservation agriculture (CA) resulted in 11-12% higher macro-aggregation compared to conventional practice (CT). • Macro-and total pores reduced in the 0-10 cm depth soil layer but increased in the 10-20 cm depth soil layer under CA. • CA resulted in 27-35% higher aggregate-associated OC content and 11% increase in OC stock at 0-30 cm.

Graphical abstract

Graphical abstract

No abstract

No abstract

Lysimetric and eddy covariance techniques are commonly used to directly estimate actual crop evapotranspiration (ETa). However, these technologies are costly, laborious, and require skills which make in situ ET estimation difficult, particularly in developing countries. With this in mind, an attempt was made to determine ETa and stagewise crop coefficient (Kc) values of transplanted puddled rice using a modified non-weighing paddy lysimeter. The results were compared to indirect methods, viz., FAO Penman–Monteith and pan evaporation. Daily ETa ranged from 1.9 to 8.2 mmday−1, with a mean of 4.02 ± 1.35 mmday−1, and their comparison showed that the FAO Penman–Monteith equation performed well for the coefficient of determination (R2 of 0.63), root mean squared error (RMSE = 0.80), and mean absolute percentage error (MAPE = 13.6 %), and was highly correlated with ETa throughout the crop season. However, the pan evaporation approach was underestimated (R2 of 0.24; RMSE = 0.98; MAPE = 22.13%) due to a consistent pan coefficient value (0.71), vegetation role and measurement errors. In addition, actual Kc values were obtained as 1.13 ± 0.13, 1.27 ± 0.2, 1.23 ± 0.16, and 0.93 ± 0.18 for the initial, crop development, mid-season, and end-season stages, respectively. These estimated crop coefficient values were higher than FAO Kc values. Statistical analysis results revealed that the overall stagewise-derived average Kc values were in line with FAO values, but different from the derived pan Kc values, although found insignificant at a 5% significance level. In addition, water productivity and agro-meteorological indices were derived to evaluate the cultivar performance in this experiment. Therefore, such a methodology may be used in the absence of weighing lysimeter-derived Kc values. The derived regional Kc values can be applied to improve irrigation scheduling under similar agro-climatic conditions.

No abstract

No abstract