Effects of Nitrogen on Soil Microbial Abundance, Enzyme Activity, and Nitrogen Use Efficiency in Greenhouse Celery under Aerated Irrigation

Abstract

The effect of n on soil enzyme activity and microbial a ated irrigation conditions was explored. The experim levels under aerated irrigation (n0, 0 kg n ha-1 ; n150, 1 200 kg n ha-1 ; n250, 250 kg n ha-1) and a control tre tional irrigation with 250 kg n ha-1). Soil bacteria, fun abundance as well as catalase and phosphatase activi then decreased with increasing n application, with ma n200 treatment. Soil nitrifier and denitrifier microbia as urease activity increased with increasing n levels a n250 treatment. Compared with the Ck treatment, enhanced soil microbial abundance by approximately and increased soil enzyme activity by 16.67 to 22.92% tion significantly promoted plant n uptake, and the n2 the highest uptake levels. Compared with Ck, celery (n uptake in the n200 and n250 treatments were si (P < 0.05). The celery yield, n agronomic efficiency, n p cy and n recovery efficiency in the n200 treatment wer and 16.07% higher compared with the n250 treatment factor productivity in the n150 treatment was 10.35% n200 treatment yet yields decreased by 20.82%. The n2 maximum yield value, net income and ratio of output 200 kg n ha-1 application with aerated irrigation effe biological environments, increases the n utilization rat n to dry matter. Abbreviations: AE, agronomic efficiency; CK, conventional irriga DAT, days after transplant; N0, aerated irrigation with 0 kg irrigation with 150 kg N ha-1 ; N200, aerated irrigation with 200 k irrigation with 250 kg N ha-1 ; PE, physiological efficiency; PFP, p of applied N; RE, recovery efficiency. I ncreasing N application is one of the main agricultura crop yield and dry matter accumulation (Guo et al., 201 The application of synthetic N to agricultural crops via cess has aided in providing foods to an estimated half of t since the Green Revolution (Erisman et al., 2008).

Irrigation Combined with Aeration Promoted Soil Respiration through Increasing Soil Microbes, Enzymes, and Crop Growth in Tomato Fields

“…Compared with the control, aeration under each irrigation level slightly increased mean values of cfub, cfuf, and cfua ( Table 1, p > 0.05), with average increases of 4.6%, 5.5%, and 3.4%, respectively. Similar results were also reported by Li et al [16], Du et al [23], and Zhu et al [25]. The increases of soil microbes under the aeration were likely due to the frequent alternation of soil dry and wet zones, thereby enhancing soil nutrient mineralization to improve microbial growth.…”

“…1 medium, respectively. Media plates were incubated at 37 and 25 • C, and the number of colonies after approximately 3 to 5 d was counted [23]. MBC was measured by the chloroform fumigation-K 2 SO 4 extraction method.…”

“…Soil dehydrogenase activity (DHA), which catalyzes dehydrogenation of organic substances and plays an intermediate role in hydrogen transformation and transfer, can be used as an indicator of the microbial redox system and is considered to be a global indicator of microbial metabolic activity in soil. However, soil biological activity can be limited by many factors, i.e., soil water and soil aeration conditions [23,24]. Very few pieces of literature were concerned with the soil microbes under AI [23,25], and the effect of AI on MBC, CA, and DHA have rarely been reported.…”

“…However, soil biological activity can be limited by many factors, i.e., soil water and soil aeration conditions [23,24]. Very few pieces of literature were concerned with the soil microbes under AI [23,25], and the effect of AI on MBC, CA, and DHA have rarely been reported. Hence, study of the soil microbe and enzyme activity (cfub, cfuf, cfua, MBC, CA, and DHA) has great significance to reveal the mechanism of CO 2 release under AI.…”

“…As noted by Li et al [16], soil enzymes are secreted by crop roots and rhizosphere microorganisms, as well as the decomposition of plant residues and microbial cells. Under the aeration, enhanced tomato root ( Figure 4) and increased soil microbes ( Figure 2) could immobilize and release nutrients into the soil and ameliorate soil fertility [23,27], which ultimately improved the CA and DHA ( Figure 3). Additionally, soil water availability affects substrate availability, O 2 concentrations, osmotic potential, gas diffusion, and cellular metabolism [24,28], thus impacting soil microbes.…”