The impact of chemical to organic fertilizer substitution on soil labile organic and stabilized N pools under intensive farming systems is unclear. Therefore, we analyzed the distribution of soil total N (STN), particulate organic N (PON), microbial biomass N (MBN), dissolved organic N (DON), and mineral N (NO₃⁻ and NH₄⁺) levels down to 100 cm profile under wheat–maize rotation system in northern China. The experiment was established with four 270 kg ha⁻¹ N equivalent fertilizer treatments: Organic manure (OM); Organic manure with nitrogen fertilizer (OM + NF); Nitrogen fertilizer (NF); and Control (CK). Results found that the OM and OM + NF treatments had significantly higher STN, PON, MBN, DON, and NO₃⁻ contents in 0–20 cm topsoil depths. Conversely, the NF treatment resulted in the highest (p < 0.01) DON and NO₃⁻ depositions in 40–100 cm subsoil depths. The NH₄⁺ contents in selected profile depths were significantly highest (p < 0.01) under OM treatment. The correlations between STN and its fractions were positively significant at 0–10 and 10–20 cm topsoil depths. Our results suggest that partial substitution of chemical fertilizer with organic manure could be a sustainable option for soil N management of intensive farming systems.

This 2-year field study analyzed plastic film mulching (PFM) effects on nitrogen use efficiency (NUE), and soil N pools under rainfed dryland conditions. Compared to no-mulching (NM, control), maize yields under PFM were increased by 36.3% (2515.7 kg ha⁻¹) and 23.9% (1656.1 kg ha⁻¹) in the 2020 and 2021 growing seasons, respectively. The PFM improved (p < 0.01) the water use efficiency (WUE) of maize by 39.6% and 33.8% in the 2020 and 2021 growing seasons, respectively. The 2-year average NUE of maize under the PFM was 40.1, which was 30.1% greater than the NM. The average soil total N, particulate organic N, and microbial biomass N contents under the PFM soil profile were increased by 22.3%, 51.9%, and 35%, respectively, over the two growing seasons. The residual ¹⁵N content (%TN) in soil total N pool was significantly higher (p < 0.05) under the PFM treatment. Our results suggest that PFM could increase maize productivity and sustainability of rainfed dryland faming systems by improving WUE, NUE, and soil N pools.

Soil extracellular enzymes are pivotal for microbial nutrient cycling in the ecosystem. In order to study the effects of different nitrogen application rates under plastic film mulching on soil extracellular enzyme activities and stoichiometry, five nitrogen application levels (i.e., 0, 90, 150, 225 and 300 kg·hm⁻²) were set based on two treatments: plastic film mulching (PM) and no film mulching (LD). We measured the soil extracellular enzyme activities (EEAs) and stoichiometry (EES) of four enzymes (i.e., β-1,4-glucosidase (βG), leucine aminopeptidase (LAP), β-1,4-N-acetylaminoglucosidase (NAG) and alkaline phosphatase (AP)) involved in the C, N and P cycles of soil microorganisms in surface soil at five maize growth stages (seedling stage, jointing stage, trumpet stage, grout stage and harvest stage). The results showed that there were significant differences in soil EEA at different maize growth stages. The soil nutrient content and soil EEA were significantly improved under PM, and the stoichiometric ratio of extracellular enzymes (E_C:N:P) was closer to 1:1:1, which indicated that PM was beneficial to the balance of soil nutrients and the activity of microorganisms. At each stage, with the increase in nitrogen application levels, the soil EEA showed a trend of increasing first and then decreasing (or remained unchanged), and both LD and PM treatments reached their highest activity at the 225 kg·hm⁻² nitrogen application rate. When the nitrogen application level was less than 225 kg·hm⁻², the soil enzyme activity was mainly limited by the N nutrient, and when the nitrogen application level reached 300 kg·hm⁻², it was mainly limited by the P nutrient. RDA and correlation analysis showed that the soil C:P, C:N, N:P and pH had significant effects on soil βG, NAG + LAP and AP activities as well as E_C:N, E_C:P and E_N:P.

Bangladesh Government has emphasized renewable energy generation and fixed a target to generate at least 150 MW of electricity from solar irrigation pumps (SIPs) by 2020; however, the generation was only about 46.98 MW. This study compared the life cycle costs (LCCs) between small solar, diesel and grid-connected irrigation pumps. The data on solar irrigation pump (SIP), diesel irrigation pump (DIP) and grid-connected irrigation pump (GIP) were collected from Birganj and Badarganj Upazilas of northern Bangladesh. The capital, maintenance, replacement and operational costs were calculated for the pumps. The outcome of annualized life cycle costs (ALCC) reveals that the average cost of the SIP (Tk.36848) is lower than DIP (Tk.105378) but marginally higher than GIP (Tk.34896). The GIP’s ALCC is the lowest, mainly for the subsidy on electric tariffs for irrigation. Therefore, at first, DIPs should be replaced by SIPs. GIPs will be replaced in the future as the price of electricity appears to be increasing. However, a small SIP’s operational cost is almost zero as it runs on solar radiation. In addition, the cost of solar irrigation will continue to fall since the price of PV panels has decreased by 12 times from 2010 to 2020.

Okra (Abelmoschus esculentus L.) plays a prominent role in the culinary traditions of various tropical and subtropical regions, such as the Southern United States, India, West Africa, and the Middle East. The nutritional contribution of okra extends to being a rich source of dietary fibre, vitamins and minerals like potassium and magnesium. Understanding the relation between okra growth and phosphorus levels can help increase agricultural yield while reducing the adverse environmental impacts. In order to support sustainable agricultural practices, this study intends to investigate the effects of varying phosphorus levels on the growth attributes and productivity of okra. The experiment was conducted at the field experimental station of Sher-e-Bangla Agricultural University (SAU), Dhaka, during the Kharif season (April to August) of 2023 using a randomised complete block design (RCBD) with four replications. The experimental treatments consisted of two okra varieties, namely 'BARI Dherosh-2' and 'Chamak' and four levels of phosphorus, viz., 0.0, 70.0, 90.0, and 110 kg P₂O₅ ha⁻¹. Data on plant height and leaves per plant were recorded at 20, 40, 60, 80, and 100 days after sowing (DAS). Days required to first flowering, number of floral buds per plant, number of pods per plant, individual pod weight, pod length and diameter, pod yield, and dry matter accumulation in different plant parts were also recorded. The result indicated that the vegetative growth parameters and yield-contributing characters were significantly improved with phosphorus fertilisation. The ‘BARI Dherosh-2’ when treated with 90 P₂O₅ ha⁻¹ resulted in maximum plant height (99.27 cm at 100 DAS), branches per plant (4.68 at 100 DAS), fruits per plant (36.65), and fruit yield (14.94 t ha⁻¹). The results were statistically similar to those obtained with the treatment combination using the same variety at 110 P₂O₅ ha⁻¹. It has been concluded that 'BARI Dherosh-2', along with a dosage of 90 kg P₂O₅ per hectare, could be a suitable dose for cultivating okra during the Kharif season in Bangladesh.