ABSTRACT
Purpose>This study explores how the land tenure system helps in protecting land quantity during agricultural production by estimating the influence of land certification on cropland abandonment, its mechanisms and its heterogeneous effects among groups at the provincial, community and household levels.Design/methodology/approach>To deal with potential homogeneity concerns, the authors investigate the impact of land certification on the area of abandoned croplands using nationally representative panel data from the 2017 and 2019 China Rural Household Panel Survey on 15,000 households across 29 provinces and time-varying difference-in-differences and propensity score matching-difference-in-differences models.Findings>Land certification significantly contributes to the protection of land quantity during agricultural production, and it reduces the area of abandoned croplands by at least 4%. This effect is mainly achieved by improving soil fertility, promoting land transfer, increasing the availability of agricultural subsidies and raising agricultural income. However, while land certification benefits farmers in nonmajor grain-producing areas and western regions, in plain, remote and nonpolitically central villages, and farmers who have not undergone land transfer or land adjustment, it is not beneficial for others.Research limitations/implications>In the postepidemic era, food security based on the protection of the amount of cultivated land becomes increasingly important. It is realistic and inevitable to rationally use every inch of cultivated land and curb the cropland abandonment by strengthening land tenure system reform, especially in the case of the insecurity of land tenure.Practical implications>There are various factors affecting farmers' cropland abandonment, such as poor soil fertility, unavailable land transfer, too little agricultural subsidies and too low agricultural income, but the root cause is the insecurity of land tenure. Empirical evidence from rural China has shown that a clear definition and effective protection of property rights can help curb the cropland abandonment. Enhancing the land protection behavior of farmers through the reform of land certification and promoting the sustainable use of land are what the reform of land tenure system should be.Social implications>Cultivated land, as the material carrier and endowment basis of grain production, is of great importance to safeguarding national food security, especially in the postepidemic era. At the present stage, it is still necessary for most developing countries to strengthen the construction of land tenure system, to carry out land certification reform and to issue farmers with clearly defined and legally effective land certificates. Equally important, efforts also should be made to promote the diversified utilization of the achievements of the certification after the completion of land certification reform in China and other developing countries.Originality/value>Expropriation and occupation of croplands are essential in protecting land quantity during rapid urbanization, and so is reducing cropland abandonment during agricultural production;therefore, it deserves close attention. In this regard, this study estimates the impact of land certification on the area of abandoned croplands, examines its possible mechanisms and identifies its heterogeneous effects to test the applicability of the property rights theory in the Chinese context and enrich the relevant literature and provide Chinese evidence for other developing countries to strengthen the protection of land quantity, by deepening the reform of the land tenure system under different circumstances.
ABSTRACT
High nitrogen (N) fertilizer inputs accelerate soil acidification and degradation in tea plantations, thus posing a threat to soil microbial diversity, species composition, and ecosystem service functions. The effects of organic fertilizer and biochar applications on improving soil fertility have been extensively studied on cropland;however, little is known about their effectiveness in promoting soil multifunctionality on rapidly expanding acidic soils in tea plantations. In this study, we conducted a two‐year field experiment in a subtropical tea plantation to investigate the effects of organic fertilizer substitution and biochar amendment on soil microbial communities and multifunctionality. The results showed that soil multifunctionality was enhanced in plots amended with organic fertilizer and biochar. Soil multifunctionality was significantly and positively correlated with alpha‐diversity of bacteria but not fungi. We also found that organic fertilizer substitution and biochar amendment improved soil multifunctionality by altering the abundance of keystone species. The abundance of keystone species classified as module hubs in the bacterial co‐occurrence network contributed significantly and positively to soil multifunctionality. In contrast, the keystone species categorized as module hubs in the fungal co‐occurrence network negatively affected soil multifunctionality. Soil pH was a key driver of soil microbial community composition, indicating that the increase in soil pH under organic fertilizer and biochar amendment had a crucial role in biological processes. These results suggest that organic substitution and biochar amendment are beneficial in preventing soil degradation and maintaining soil multifunctionality in subtropical tea plantations.
ABSTRACT
In rapidly growing urban areas, such as Tijuana, Mexico, the presence of urban green spaces (UGSs) can help stem soil erosion, improve infiltration, slow runoff, decrease flooding, reduce air pollution, and mitigate climate change. In many water-scarce parts of the world, where centralized wastewater treatment is not accessible or practical, decentralized wastewater treatment systems (DEWATSs) have the potential to supply the water needed for irrigating UGSs. Here, we first review UGS systems supported by DEWATSs and the water quality guidelines and challenges associated with implementing DEWATSs for urban greening in different countries, including Mexico. We also critically examine the linkages between the lack of UGSs in Tijuana, Mexico, extensive soil erosion, and failing sanitation infrastructure that has led to the infamously poor water quality in the Tijuana River. Tijuana’s Ecoparque Wastewater Treatment Facility, a low-energy, aerobic DEWATS, which collects, treats, and discharges residential sewage for localized landscape irrigation, demonstrates how DEWATSs can meet the water demands for urban greening in rapidly urbanizing cities. The aerobic decentralized treatment using a gravity-fed trickling biofilter resulted in a >85% removal of chemical oxygen demand and dissolved organic carbon. Prior to treatment facility upgrades, there was a ~2 log reduction in total coliform and Escherichia coli and a <20% decrease in ammonia from the influent to final effluent. After the addition of a maturation pond in 2020, the effluent met Mexico standards for irrigation reuse, with a ~4 log reduction in fecal coliforms from the influent to final effluent. Case study results demonstrated the potential for decentralized wastewater treatment to meet effluent standards for landscape irrigation, provide water for urban greening, and prevent pollution in the Tijuana River and other urban waterways.