Soil Physicochemical Properties Variation in Black Soil after the Long-term Application of Different Organic Amendments

Aims: This research aimed to assess how the physicochemical properties of black soil respond to different organic amendments after 10 years of application.

Study Design: The experiment was established in 2010 and followed a randomized block design consisting of 24 plots (5 m × 5 m) 25 m2 with eight treatments in three replicates.

Place and Duration of Study: The study site was located at the Jilin Agricultural University Research Farm, Northeast China (43°48′ N, 125°23′ E; km).

Methodology: The treatments for the study included an annual input of chemical fertilizer and organic amendments at the surface of the soil. The treatments were: Control (CK), chicken manure (JM), fodder grass (FG), mushroom (MS), maize straw (MZ), tree leaf (TL), pig manure (PM) and cow manure (CM). Chemical fertilizers were added at the rate of 165 kg of N, 82.5 kg of P and 82.5 kg of K ha_1 per year. Application rates of organic materials were adjusted to similar amounts of organic matter (2000 kgha−1). In June 2019, soil samples were collected from each of the amended fields. In each field, three sampling points were randomly selected. Soil samples were collected from the 0 – 20 cm depth using a core sampler then taken to the laboratory for soil physicochemical properties analysis.

Results: Comparing the results of the organic treatments with CK, bulk density decreased by 5.6-18.0% while porosity, EC, pH, total N and SOC significantly increased in the organic treatments by 6.0-25.9%, 8.3-25.0%, 0.52-1.7%, 2.7-54.7% and 1.3-18.4% respectively. The textural class of soil under the different treatments did not change however, the distribution of soil particle size varied among the treatments, where high clay and silt content were recorded in the amended fields. Moreover, the application of different organic materials significantly affected the soil aggregate stability and this was attributed to the increase in organic matter content which accelerated important microbial activities in the soil to improve aggregation. At higher suction potentials, higher water contents were recorded in the organic amended fields mainly due to the improved physical properties of the soil.

Conclusion: The study results showed that the application of organic amendments greatly improves the physical and chemical properties of black soil. Therefore, using these organic amendments can serve as an effective strategy to enhance soil quality and fertility.