Abstract
Understanding nitrogen (N) release patterns and kinetics is a key challenge for improving N use efficiency in any agroecosystem. An incubation experiment was done to study the N release pattern and kinetics of contrasting soils amended with compost (CO), poultry manure (PM), rice husk biochar (RHB), poultry manure biochar (PMB) and cowdung (CD) combined with chemical fertilizer (integrated plant nutrient system, IPNS approach) under two moisture regimes, viz. field capacity (FC) and continuous standing water (CSW) at 25 °C for 120 days. Our results revealed that NH4+-N was the dominant under CSW conditions, whereas NO3−-N was dominant under FC conditions. Net mineral N data fitted well to the first order kinetic model. Both N release potential (N0) and rate constant (k) were greater in acidic soil than those of charland soil. The maximum N release varied between 24.90–76.29% of input depending on soil type and moisture status. N mineralization was strongly correlated with urea N application. PM and PMB mineralized in all soil and moisture conditions whereas N immobilization was observed in the case of RHB. N mineralization was strongly correlated with urea N application. Gaseous N losses were different for the organic amendments exhibiting more gaseous N losses in PM, CD and CO based IPNS whereas the lowest gaseous N loss was observed in PMB based IPNS. Biochar based IPNS increased soil pH in all conditions. Thus, the present study suggests that N release depends on soil type, soil moisture and type of organic amendment. However, CO, PM and CD based IPNS can be recommended for both acidic and charland soils in terms of N release as short duration crops will suffer from N deficiency if biochar based IPNS is used in the field.
Highlights
In Bangladesh, SOM content is dwindling day by day as a result of inadequate management, intensive manipulation, and excessive use of chemical fertilizer
With regard to soil moisture status, the mean NH4 + -N was significantly higher in soils kept under continuous standing water (CSW) compared to the soils kept under field capacity (FC), being 35.47 and 8.38 mg N kg−1 soil, respectively, in CSW and FC, irrespective of all other factors (Table 4)
The highest mean NH4 + -N release was observed in compost + chemical fertilizer (CO + CF), which was identical to cowdung + chemical fertilizer (CD + CF) and poultry manure + chemical fertilizer (PM + CF), whereas the lowest value was observed in poultry manure biochar + chemical fertilizer (PMB + CF) (Table 4)
Summary
In Bangladesh, SOM content is dwindling day by day as a result of inadequate management, intensive manipulation, and excessive use of chemical fertilizer. In order to improve crop yields, minimize contamination, and attain sustainable farming, fertility in these soils must be maintained or restored to a sufficient level [3,4]. An integrated plant nutrient system (IPNS) is an approach that allows for the applying of nutrients from both organic and inorganic sources to reduce the application of synthetic fertilizers, achieve a close fit between nutrient supplies and plant nutrient demands, maintain soil health, and provide a continuous nutrient supply to plants. Organic amendment (OA) is an important nutrient supplier to the plants and a means of soil rejuvenation [5,6]. Organic amendments are most effective when combined with mineral fertilizers [7,8]. OA, especially cowdung (CD), poultry manure (PM) and biochar (BC), improves soil physical properties [9,10], chemical properties [11,12], and biological properties [13]
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