Abstract
The rapid development of cities in the recent 10 years caused a reduction in the cultivated land area, which only accounts for 14% of the total land area in China. Land development and reclamation have been regarded as an effective way to compensate farmland occupation. However, most of the newly reclaimed land has poor soil fertility and suitability; in some cases, the production capacity is only 10–30% of the occupied farmland. In order to ameliorate the soil quality of the newly reclaimed land, this study evaluated the effects of commercial organic fertilizer (0.75, 1.50, and 2.25 kg/m2), mushroom residue (1.50, 2.25, and 3.00 kg/m2), biogas slurry (150, 225, and 300 kg/m2), vegetable cake (0.30 and 0.60 kg/m2), and chemical compound fertilizer (37.50 g/m2) on the pH, moisture content and organic matter content (OMC), available phosphate, total nitrogen, alkaline hydrolysis nitrogen, microbial biomass carbon and nitrogen, and number of total bacteria and phosphate-solubilizing bacteria, as well as the growth of maize seedlings. The results from this study indicate that the soil quality (OMC is an indicator) was ameliorated by chemical and organic fertilizers, in particular commercial organic fertilizers, which caused a 9.35–16.35% increase in moisture content, a 11.56–18.72% increase in pH, a 1.73–2.15 fold increase in OMC, a 338.44–491.41% increase in available P, a 36.80–48.14% increase in total N, a 95.32–128.34% increase in alkaline hydrolysis N, a 92.57–178.38% increase in total bacterial numbers, and a 7.57–20.87 fold increase in microbial biomass carbon compared with the control. The pot experiment further indicated that soil amended with commercial organic fertilizers caused a 20.35–30.55% increase in the height and a 12.50–16.67% increase in the total dry weight of maize seedlings. In addition, representative strains with the ability to dissolve phosphorus and fix nitrogen were successfully isolated using the culture method, and were then identified based on colony morphological observation and 16S rDNA sequence analysis, which help us to not only understand why organic fertilizer has great effect on soil improvement, but also provides beneficial microbial resources for further study.
Highlights
Introduction distributed under the terms andAs a result of the rapid development in urbanization over the last 10 years, a large number of farmland has been occupied in China, and a decrease in the amount of cultivated land, which is the basic element of agricultural production, is an inevitable trend [1,2]
The results from this study indicated that the moisture content, pH, and organic matter content (OMC) were differentially affected by four kinds of organic fertilizers at different concentrations
The moisture content was significantly increased by commercial organic fertilizer at 0.75, 1.50, and 2.25 kg/m2 ; mushroom residue at 1.50 kg/m2 ; and vegetable cake at 0.60 kg/m2, while the moisture content was significantly decreased by the biogas liquid at 300 kg/m2
Summary
As a result of the rapid development in urbanization over the last 10 years, a large number of farmland has been occupied in China, and a decrease in the amount of cultivated land, which is the basic element of agricultural production, is an inevitable trend [1,2]. The cultivated land area only accounts for 14% of the total land area in China [3]. Cultivated land resources are seriously insufficient because of farmland occupation. In order to achieve food security, a balance of occupation and compensation has been proposed in China, while land development and reclamation have been vigorously implemented over the past 10 years [3]. There are various problems in the implementation of a balance system of cultivated land occupation and compensation. The main issue is that the quality of the supplementary cultivated land is not consistent with the quality of the occupied cultivated land; for example, Hu et al [1] reported that the production capacity of some newly reclaimed land is only 10–30% of the occupied farmland based on the quality investigation of the occupied farmland in Hangzhou of Zhejiang Province in the last five years
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