Impacts of Soil Aggregation on Nitrogen Storage and Supply in Biomass Incorporated Sandy-Loam Acidic Soil

Soil aggregation plays a critical role in the maintenance of soil nutrient storage and supply. After five years of crop biomass management, field samples from a sandy loam mountain hilly soil were examined for aggregate distribution, physical subfractions within aggregates, and organic nitrogen (N) fractions, such as nonhydrolyzable N (NHN), hydrolysable ammonium N (HAN), amino-sugar N (ASN), amino-acid N (AAN), and hydrolysable unidentified N (HUN). The total N pool and theoretically mineralizable N were used to calculate the soil N storage and supply capacity, respectively. The total N, mineralizable N, and coefficient of mineralisation rate were all considerably raised by crop biomass incorporation. Analysis of covariance structures showed that the organic N fractions had an impact on the supply and storage of N in the soil, with HUN and AAN contributing the most to the potentially mineralizable N and; also HUN and AAN making up the largest portion of the total soil N pool. In comparison to bulk soils that had not had biomass removed, the amounts of organic N components HAN, ASN, AAN, HUN, and NHN were higher by 98.2%, 87.2%, 71.47%, 38.91%, and 43.27%, respectively. Compared to microaggregates, biomass incorporation enhanced soil macroaggregates by 9.37% and had higher organic N percentages and accumulation efficiency. The mineralizable N was significantly correlated with all fractions of N. The inorganic nitrogen and total nitrogen (TN) were higher in 100% biomass inclusion-T₅ (60.01 and 841.58) and lowest in total removal of biomass-T₁ (24.92 and 479.74). The > 2 mm aggregate size significantly contributed more in organic N fractions rather than 2–0.25 mm or less.