Introduction

Environment-friendly farming practices are crucial to achieving sustainable agricultural development. In recent years, promoting the adoption of environment-friendly farming practices has become a major challenge in various regions, including the European Union, Ethiopia, Vietnam, and China (Teklewold et al., 2013; Luo et al., 2016; FAO, 2017; Thi et al., 2021). Among them, the reduction of chemical fertilisers, which is one of the primary sources of non-point source pollution (Smith and Siciliano, 2015), has attracted significant attention. As the global population continues to increase, agriculture uses over 200 million tons of chemical fertilisers annually to meet rising food demand (Wu et al., 2018). However, reducing the use of chemical fertilisers is not a trade-off for reduced crop yields, as overuse of chemical fertilisers creates only environmental costs and no economic benefit (Wuepper et al., 2020). Consequently, reducing fertiliser use is increasingly becoming a central focus for environment-friendly farming practices.

Nevertheless, few studies investigate the effects of land certification on chemical fertiliser use, despite its significant impact on agricultural production (de Soto, 2000). Land certification is a practical embodiment of land tenure definition and forms the core of land tenure reform (Zheng et al., 2023). With the widespread implementation of land certification programmes, a growing body of relevant literature has begun to link land tenure reform to environment-friendly farming practices (Deininger and Jin, 2006; Tsegaye et al., 2012; Teklewold et al., 2013; Lovo, 2016). For example, Thi et al. (2021) and Saint-Macary et al. (2010) show that land tenure in Vietnam is highly associated with environment-friendly farming practices, such as the use of organic fertiliser and agroforestry. According to Holden et al. (2009) and Mengesha et al. (2019), land certification in Ethiopia contributes to environment-friendly farming practices such as terracing, tree planting, and composting on land. While some scholars have considered organic fertiliser use to be environmentally friendly and found a strong substitution relationship between organic and chemical fertilisers (Khamwichit et al., 2006), relevant studies on the nexus between land certification and chemical fertiliser use remain scarce, especially for developing countries such as China (Hu et al., 2021; Zheng et al., 2021). China is not only the largest producer of chemical fertilisers but also one of its largest consumers (Liu and Diamond, 2005; Guo et al., 2021). Moreover, China has just implemented a new round of land certification reform (‘new reform’ henceforth) nationwide in 2013 (Zheng and Qian, 2022). This provides a unique opportunity to reveal the link between land tenure reform and environment-friendly farming practices by investigating the effects of land certification on chemical fertiliser use. Specifically, this study aims to answer the following questions: (i) Can the new reform reduce farmers’ use of chemical fertilisers? (ii) If so, what are the underlying mechanisms? (iii) Are there any heterogeneity in the impact of the new reform on farmers’ use of chemical fertilisers across different land tenure states?

This study may add to the literature as follows: First, it combines land tenure reform with environment-friendly farming practices, and quantitatively assesses the impact of land certification on farmers’ chemical fertiliser use. This helps to address the knowledge gap in the ecological effects of land certification and provides insights into environment-friendly farming practices from the perspective of land tenure reform. Second, since the new certification is not a randomised experiment in the sense of natural science, we utilise a propensity score matching and difference-in-differences regression approach to mitigate endogeneity problems caused by selection bias and time-invariant unobserved factors, and a mediation effects model to estimate how land certification affects farmers’ chemical fertiliser expenditures, and its mechanisms and heterogeneous effects. Finally, exploiting the latest nationally representative panel data from the Chinese Family Database, it discusses the real and pressing land tenure security and chemical fertiliser overuse issues facing most developing countries. It proposes a reference solution for China and other developing countries to promote sustainable agricultural development.

The rest of the article is structured as follows. Section “Institutional background and theoretical analysis” reviews the institutional background and makes a theoretical analysis. Section “Research design” introduces datasets, variables, and empirical strategies. Section “Impact of land tenure reform on environment-friendly farming practices” presents baseline results and robustness tests, as well as exploring the impact of land certification on other aspects of environment-friendly farming practices. Section “Mechanisms of land tenure reform on environment-friendly farming practices” discusses the underlying mechanisms. Section “Heterogeneous effects of land tenure reform on environment-friendly farmingpractices” analyses heterogeneity, and Section “Conclusions and discussion” concludes with policy implications and discussion.

Institutional background and theoretical analysis

Land certification reform in rural China

Secure and well-defined land property rights are important for developing countries to enhance agricultural productivity and protect land owners’ rights and interests (de Janvry et al., 2015). To reform and formalise land property rights, developing countries have widely implemented land certification since the 1960s, with support from international organisations such as the World Bank and the Food and Agriculture Organization of the United Nations (de Soto, 2000).

China’s land certification reform started in the late 20th and early 21st centuries. Specifically, the Notice on Further Stabilising and Improving Rural Land Contracting Relations launched the first round of rural land certification reform in 1997 since the reform and opening-up, which required county governments and above to uniformly issue land contract management rights certificates to farmers. This document’s spirit was incorporated into subsequent law. The Land Management Law of the People’s Republic of China in 1998 made the issuance of land certificates to farmers a requirement. However, although China’s central government attaches great importance to land certification, the degree of implementation of certification was not high (Zheng et al., 2023). Ye et al. (2000) found that >60% of Chinese villages did not issue land management contract certificates to farmers, although county-level and above governments did print them. Thus, land adjustments between different farmers have been common since the late 20th century. Further, after the implementation of the Land Contract Law of the People’s Republic of China, the Chinese central government initiated the second round of land certification reform in 2003, which was well implemented in pilot areas. Some scholars estimate that in pilot provinces such as Zhejiang, Anhui, and Hunan, >94.6% of farmers obtained land certificates in 2007 (Yu and Shi, 2012). However, prior to the promulgation of the Property Law of the People’s Republic of China in 2007, land contract management rights were considered creditor rights rather than real rights. Moreover, land certificates remained sketchy, with unclear land information on parcel size and boundaries. Therefore, farmers’ land property rights were unprotected by powerful laws at that time. Consequently, China’s No. 1 Central Document in 2008 proposed to accelerate the establishment of a system of land contract management rights registration and ensure that land certificates reach all farmers, emphasising the usage of land certification to promote the protection of land property rights.

The Chinese government announced the new reform in 2013 through a No. 1 Central Document, mandating the issuance of land certificates to every farmer within five years. Since then, the new reform has been in full swing across China. There may be some differences in the specific implementation of each province, but the new reform in rural China generally follows a five-step procedure: (i) Village cadres collect the land information of the farmers and make a basic information table for the farmer’s land certification; (ii) Mapping technicians use drones, geographic information system (GIS) and global positioning system (GPS) technology to map the size, location, and number of land plots and complete land certification forms; (iii) Village cadres publicize land registration information and assist farmers in handling various land disputes during this period; (iv) Village cadres submit accurate land registration information to the local government; (v) The local government makes land certificates and entrusts village cadres to issue them to each farmer. According to public data from the Ministry of Agriculture and Rural Affairs of China, by the end of 2020, the new reform has been substantially completed and over 200 million farmers have received new land certificates (Zheng et al., 2023).

Theoretical analysis of the impact of land certification on chemical fertiliser use

The new reform offers distinct advantages over past reforms. First, the attribution boundary is clearer. The new reform uses modern mapping technologies such as drones, GIS and GPS to define land physical boundaries, and it employs the latest legal texts on the three separation of land rights (collective ownership, contractual rights and operating rights) to determine land legal boundaries. Second, property rights are more complete. Upon certification, farmers are granted exclusive income rights, exclusive use rights, and the freedom to transfer their land. Third, legal protection is more stringent. The new reform requires the establishment of a unified registration system and the full and timely issuance of legally valid land certificates to farmers, which is more conducive to the legal protection of land tenure. Consequently, with these benefits, the new reform can theoretically motivate farmers to increase long-term investment and land rent-in, and reduce off-farm employment, thus promoting the reduction of chemical fertilisers (Fig. 1).

Fig. 1: Analytical framework.
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Source: Organized by the author.

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First and foremost, the new reform reduces farmers’ use of chemical fertilisers by increasing long-term investment. According to property rights theory, security of land tenure is conducive to investment, and vice versa (Holden et al., 2009). In general, insecure land tenure can exacerbate farmers’ short-term behaviour (Besley, 1995; Deininger et al., 2011). However, the new reform improves land tenure security, making the protection of property rights shift from creditor’s right protection to real right protection (Zheng and Qian, 2022). In this case, farmers cherish their land more and are willing to increase long-term investment, particularly in organic fertilisers (Abdulai et al., 2011; Zheng et al., 2023). Due to the substitution relationship between organic and chemical fertilisers (Khamwichit et al., 2006), the increase in organic fertilisers resulting from land certification will reduce the use of chemical fertilisers accordingly.

Next, the new reform reduces farmers’ use of chemical fertilisers through land rent-in. Under the household responsibility system (HRS), the widespread existence of smallholders is an important reason for overuse of chemical fertilisers in China (Ju et al., 2016; Wu et al., 2018). Compared to large-scale farmers, the fertiliser used by smallholders is inefficient and excessive due to a lack of knowledge and technology and fragmented land (Luo et al., 2016). Expanding the size of the farm by increasing land rent-in can save on chemical fertiliser inputs (Ren et al., 2021). Wu et al. (2018) confirm that a 1% increase in farm size is correlated with a statistically significant 0.3% decrease in fertiliser use per hectare. As a result, land rent-in stimulated by the new reform (Xu and Du, 2021) is likely to lead to a decline in chemical fertiliser use.

Finally, the new reform reduces farmers’ use of chemical fertilisers by reducing off-farm employment. Off-farm employment is an important driver of overuse of chemical fertilisers. On the one hand, off-farm employment often reduces the supply of agricultural labour, requiring farmers to apply additional chemical fertilisers to compensate for labour shortages (Wu et al., 2018). On the other hand, remittance income from off-farm employment enhances the availability of chemical fertiliser for farmers, thus increasing the likelihood of its application (Caulfield et al., 2019). As land certification incentivises farmers to engage in agricultural production by protecting their land rights and interests (Galiani and Schargrodsky, 2010), the likelihood of farmers participating in off-farm employment has decreased (de Brauw and Mueller, 2012). Consequently, the new reform decreases the application of chemical fertilisers (Hu et al., 2021).

Research design

Data source

The research data comes from the Chinese Family Database (CFD), which is collected by Zhejiang University in China. CFD uses a stratified, three-stage sample proportional to population size (Qian, 2020). It is implemented as follows: (i) China’s counties (districts and county-level cities) in 29 provinces are divided into ten tiers according to per capita GDP, and sample counties are randomly selected by stratification. (ii) Communities (villages) are randomly selected from the counties. (iii) Households are randomly selected from the selected communities. According to the final sampling rule, approximately 20 farmer households are randomly selected for interviews in each sample village. We investigated the impact of the new reform on farmers’ fertiliser use by considering a sample of farmers engaged in agricultural production and retaining key variables: land certification, land adjustment, fertiliser expenditure and use, household head characteristics, family characteristics, etc. However, 59 observations with missing answers and 4 observations that failed to match were omitted from the 25,440 original samples (loss rate: 0.25%). Moreover, although the CFD has collected data covering the entire new reform process since 2011 and conducts national tracking surveys every two years, information on farmers’ fertiliser expenditures was unavailable before 2013. Thus, a unique household-level non-balanced panel data of 25,377 observations for 2015, 2017, and 2019 was obtained.

Variable selection

Besides the CFD and existing literature, the variables are selected as follows.

  1. (1)

    Dependent variable: Fertiliser expenditure. This study uses fertiliser expenditure as a proxy variable for environment-friendly farming practices, which is based on the survey question, ‘How much was your family’s chemical fertiliser expenditure for agricultural production and operation last year? (unit: yuan)’. CFD shows that fertiliser expenditures in 2015, 2017, and 2019 were 140.297, 128.015, and 125.656 yuan per mu, respectively, showing a decreasing trend. Due to the large variation in fertiliser expenditure, it is presented in logarithmic form during the estimation. Note that both chemical fertiliser expenditure and use can reflect farmers’ behaviour regarding fertiliser use (Ma et al., 2018). We utilised chemical fertiliser expenditure because the dependent variable as expenditure has many more observations than use, as the latter information has only been collected since 2017. To reduce measurement error for the dependent variable, chemical fertiliser use is also used for the robustness check.

  2. (2)

    Core independent variable: Land certification. This variable is based on the survey question, ‘In which year did the village carry out land certification’? As mentioned earlier, this study considers the new reform to be the actual certification of land in villages after 2012. This means that in CFD data from 2015 to 2019, the time span before and after the new reform is from −6 (2013–2019) to 4 (2019–2015). Moreover, CFD shows that the new reform at the village level in 2015, 2017, and 2019 was 15.97%, 52.91%, and 90.73%, respectively, showing an increasing trend. This is contrary to the trend in farmers’ fertiliser expenditures, and preliminary evidence indicates a negative correlation between land certification and fertiliser expenditures.

  3. (3)

    Control variables. Based on available data and existing studies, control variables are household head and family characteristics. Household head characteristics include age, age squared, and education (Teklewold et al., 2013; Mengesha et al., 2019; Guo et al., 2021). Family characteristics include the existence of a village cadre in the family, the value of machinery and livestock, the proportion of family farm labour, the area of cultivated land, the number of cultivated land plots, and land market value (Latruffe and Piet, 2014; Ju et al., 2016; Thi et al., 2021). These controlled the potential impacts of family social and economic capital, human capital, and resource endowments. The definitions and descriptive statistics for the selected variables are detailed in Table 1.

    Table 1 Variable definition and summary statistics.
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Identification strategies

In rural China, the new reform was first implemented as a pilot and then gradually rolled out. Taking advantage of the gradual characteristics of land certification, this study can use a staggered difference-in-difference (DID) model to compare the differences in fertiliser behaviour between certified and uncertified farmers over different periods and conduct a causal analysis. However, differences in fertiliser behaviour between certified and uncertified farmers may be due to factors related to individual and household characteristics rather than the exogenous impact of the new reform, resulting in selection bias in estimation results. In this case, the combination of propensity score matching (PSM) and DID is widely recognized as a preferred option to address the additional selection bias associated with unobservable time-invariant heterogeneity (Heckman et al., 1997). Therefore, we adopt a PSM-DID approach for estimation.

Propensity score matching

Following the PSM-DID research design, this study first constructs a reasonable counterfactual framework by selecting individuals in the control group with covariates similar to those in the treatment group as matching objects (Rosenbaum and Rubin, 1983). Specifically, drawing on Zheng and Qian’s (2022) research, we select the commonly used “one-to-one” neighbour matching method with a calliper range of 0.05, and adopt the binary logit model to estimate propensity score. The model settings are as follows:

$$\mathrm{ln}\left(\frac{{\rho }_{i}}{1-{\rho }_{i}}\right)={\alpha }_{0}+\alpha {{\boldsymbol{X}}}_{i}+{\varepsilon }_{i}$$
(1)

where \({\rho }_{i}\) = \(\rho ({{\boldsymbol{X}}}_{i})\)=\({P}_{r}({T}_{i}=1|{{\boldsymbol{X}}}_{i})\) represents the propensity score of the sample farmers, while \({\alpha }_{0}\), \({\boldsymbol{X}}\), \(\alpha\), \({\varepsilon }_{i}\) represents the intercept term, covariates and its parameters to be estimated, and the random disturbance term, respectively.

Figure 2 presents the results of the balanced test using the PSM model. The results indicate that the absolute value of the standard deviation of each variable post-matching falls significantly below 10%, suggesting that the variable attributes of the two groups of samples are considerably similar following propensity score matching, thus satisfying the balance test. Furthermore, as depicted in Fig. 3, most samples fall within the common support domain after matching, demonstrating the success of the matching process. These findings strongly support the application of PSM-DID estimation in this study.

Fig. 2: Standardization bias before and after matching.
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Source: Organized by the author.

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Fig. 3: The common support of propensity scores.
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Source: Organized by the author.

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Staggered DID model

To further control the possible unobservable variables, on the basis of using the PSM method to reduce the interference of observable factors, this study applies a staggered DID model to identify the causal effect of land certification on farmers’ chemical fertiliser expenditures. The regression equation is as follows:

$${\mathrm{ln}}({y}_{{vit}})={\beta }_{0}+{\beta }_{1}{Certi}{f}_{{vt}}+\beta {{\boldsymbol{X}}}_{{vit}}+{\mu }_{i}+{\gamma }_{t}+{\varepsilon }_{{vit}}$$
(2)

where subscripts v, i, t represent the village, farmer, and survey year, respectively. \({\mathrm{ln}}({y}_{{vit}})\) denotes the logarithm of farmers’ chemical fertiliser expenditures per mu. \({Certif}\) is land certification’s dichotomous dummy variable. If the village \(v\) conducts land certification in year \(t\), for \(t\) >=\(\tau\), the value of land certification is 1 and 0 otherwise, where \(\tau\) >=2013. \({\beta }_{0}\) is the intercept term; \({\beta }_{1}\) is the estimated coefficient of land certification; \(\beta\) are the parameters of control variables to be estimated; \({\boldsymbol{X}}\) indicates a series of control variables. \({\mu }_{i}\) represents the Household FE controlling for factors such as the farmers’ ability and preference. \({\gamma }_{t}\) represents the Year FE controlling for time-varying factors such as national policies or macroeconomic conditions that change over time but do not change with farmers. \({\varepsilon }_{{vit}}\) is the random disturbance term.

To further investigate whether treatment and control groups had the same trends of change before the reform, we use an event study method to test the parallel trend hypothesis. As can be seen from Fig. 4, prior to land certification, there was no significant difference between treatment and control groups. However, after the completion of land certification, the inhibitory effects of land certification on farmers’ chemical fertiliser expenditure per mu showed an increasing trend year by year. This suggests that, in this study, the parallel trend assumption is met, and land certification has a certain positive impact on reducing farmers’ chemical fertiliser expenditures.

Fig. 4: Land certification and fertiliser expenditure: Parallel trend test.
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The preceding land certification period (pre_1) is used as the base period. Pre represents that the land certification time is after the data collection time, while Post represents that the land certification time is before the data collection time. Robust standard errors are clustered at the village level at the 95% confidence level. Source: Organized by the author.

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Mediation effects model

After clarifying the link between land certification and fertiliser expenditure, we further construct mediation effects models to examine the underlying mechanisms mentioned in the theoretical analysis section. Specifically, we combined the CFD questionnaire to measure these mechanism variables: ‘Did your family use organic fertiliser last year?’ (yes = 1, no = 0), ‘Did your family rent any land from others last year’? (yes = 1, no = 0), and ‘What was the share of non-farm employment in your family last year’? (0–1). The specific model takes the following form:

$${M{ed}}_{{vit}}={\lambda }_{0}+{\lambda }_{1}{Certi}{f}_{{vt}}+\lambda {{\boldsymbol{X}}}_{{vit}}+{\mu }_{i}+{\gamma }_{t}+{\varepsilon }_{{vit}}$$
(3)
$${\mathrm{ln}}({y}_{{vit}})={\gamma }_{0}+{\gamma }_{1}{M\text{ed}}_{{vit}}+{\gamma }_{2}{Certi}{f}_{{vt}}+\gamma {{\boldsymbol{X}}}_{{vit}}+{\mu }_{i}+{\gamma }_{t}+{\varepsilon }_{{vit}}$$
(4)

where \({Med}\) represents the three mediating variables in this study: long-term investment, land renting, and off-farm employment. \({\lambda }_{0}\) and \({\gamma }_{0}\) are the intercept terms; \({\lambda }_{1}\), \(\lambda\), \({\gamma }_{1}\), \({\gamma }_{2}\), and \(\gamma\) are the parameters to be estimated; \({\mu }_{i}\), \({\gamma }_{t}\), and \({\varepsilon }_{{vit}}\) are set in accordance with Eq. (2). If coefficients \({\lambda }_{1}\) in Eq. (3) and \({\gamma }_{1}\) in Eq. (4) are both significant, land certification affects farmers’ chemical fertiliser expenditure through these mediating variables. Accordingly, if coefficient \({\gamma }_{2}\) is still significantly negative and decreased compared with coefficient \({\alpha }_{1}\) in Eq. (1), the mediating variable plays a partial mediating role. If coefficient \({\gamma }_{2}\) is insignificant, the mediating variable plays a complete mediating role.

Impact of land tenure reform on environment-friendly farming practices

Baseline results

Table 2 presents estimates of the impact of land certification on farmers’ chemical fertiliser expenditures based on the PSM-DID approach. In column (1), only land certification, household fixed effects, and time fixed effects are included. In column (2), the control variables mentioned in Table 1 are further included to control for unobservable time-varying factors. The results show that regardless of control variables, land certification exerts an inhibitory effect on chemical fertiliser expenditures, which is statistically significant at the 1% level. Compared to non-certified farmers, certified farmers experienced a reduction of about 15% in chemical fertiliser expenditures. These results suggest that issuing land certificates with legal effects and multiple economic uses to farmers will help reduce soil health damage from chemical fertiliser overuse, thereby promoting land conservation and sustainable agricultural development.

Table 2 Land certification and fertiliser expenditure: Baseline results.
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Robustness checks

Table 3 presents three scenarios for robustness checks. First, in the benchmark regressions, we determine the new reform’s start time as 2013 according to the 2013 No. 1 Central Document. However, some rural areas in China conducted a small pilot as early as 2009 according to the No. 1 Central Document in 2009 (Xu and Du, 2021). Thus, to mitigate endogenous problems caused by measurement bias, we first redefine village-level land certification (yes = 1, no = 0) as the core independent variable since 2009. Column (1) shows that the coefficient of land certification1 is −0.159 and statistically significant at 1%. This is highly robust with the baseline results in Table 2, possibly due to the small number of pilot samples during 2009–2013 (only 2.18% of the total sample), which would not affect the validity of the estimates.

Table 3 Land certification and fertiliser expenditure and use: Robustness checks.
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Second, based on data availability and Ma et al. (2018) studies, we preferentially select fertiliser expenditure as the dependent variable. However, the amount of fertiliser farmers use is also a common proxy variable for farmers’ fertiliser use behaviour (Wu et al., 2018), although it may be easier for surveyed farmers to answer regarding chemical fertiliser expenditures. Hence, to doubly verify the robustness of the estimates, the amount of fertiliser farmers used per mu (unit: kg) is re-estimated as the dependent variable. Column (2) shows that land certification also exerts a negative and statistically significant impact on chemical fertiliser use per mu, indicating a clear benefit for land conservation and sustainable agricultural development.

Third, considering that land and non-land lessees have various interest orientations and resource endowments, their fertiliser use behaviour may differ. To reduce the potential interference of land lessees with the estimated results, we exclude farmers with land-renting behaviour. Column (3) indicates that the coefficient of land certification is still negative and significantly different from zero, suggesting that certified farmers are also less likely to spend too much money on chemical fertilisers. Again, these results still support previous estimates.

Impact of land certification on other aspects of environment-friendly farming practices

Environment-friendly farming practices are an umbrella term for a range of sustainable development practices that help preserve natural resources and the natural environment, of which the reduced use of chemical fertilisers is only one aspect. As mentioned earlier, terraces, tree planting, straw recycling, composting on land, and the use of farm manure and organic fertiliser are also manifestations of environment-friendly farming practices. Thus, there is still a need to further explore other aspects of environment-friendly farming practices, despite our earlier examination of chemical fertiliser use.

Combined with data availability, here we mainly examine the impact of land certification on straw recycling and farm manure use. Since only 2019 data are available for the straw recycling variable (yes = 1, no = 0), we employ the logit model for estimation; there are 2017 and 2019 data for the farm manure use variable (yes = 1, no = 0), we estimate it using a panel logit random effects model. Table 4 presents the average marginal effects of land certification. Results in column (1) reveal that land certification significantly increases the probability of straw recycling by 2.7%. Meanwhile, the estimates in column (2) show that certified farmers are 14.7% more likely to use farm manure than uncertified farmers. These findings suggest that land certification enhances environment-friendly farming practices for farmers in several ways beyond simply reducing chemical fertiliser use.

Table 4 Land certification and other aspects of environment-friendly farming practices.
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Mechanisms of land tenure reform on environment-friendly farming practices

Previous estimates support the hypothesis that land certification significantly helps reduce farmers’ chemical fertiliser expenditures per mu. Then, how does land certification reduce fertiliser expenditure? Table 5 reports the estimated results of the mechanism tests. The estimated coefficients of land certification for long-term investment in column (1), land renting in column (3), and off-farm employment in column (5) are 0.066, 0.033, and −0.014, respectively; they are in line with theoretical expectations and statistically significant. These results reveal that land certification has a significant promoting effect on long-term investment and land rent-in but a significant inhibiting effect on off-farm employment for farmers. As land certification increases the use of organic fertiliser, in fact, this also suggests that land certification promotes environment-friendly farming practices from another perspective.

Table 5 Land certification and fertiliser expenditure: Mechanism tests.
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After considering the effects of long-term investment, land leasing, and off-farm employment, the estimated coefficients of land certification in columns (2), (4), and (6) continue to show a significant negative relationship. Furthermore, compared to the benchmark regression results in column (1) of Table 2, these coefficients exhibit a slight decrease in magnitude. To sum up, the above evidence implies that land certification mainly reduces fertiliser expenditure through mechanisms such as increasing long-term investment, leasing land and inhibiting off-farm employment, and the three mediating variables play a partial mediating role.

Heterogeneous effects of land tenure reform on environment-friendly farming practices

As mentioned earlier, the Chinese government has implemented several rounds of land certification programmes since the last century, and land adjustments based on population changes have also occurred frequently. This indicates that prior to the new reform, there may have been many initial differences in land tenure security among farmers, and their preferences for reform may also be inconsistent. To more accurately identify the fertiliser reduction effects of land certification, it is necessary to thoroughly investigate its heterogeneous effects on chemical fertiliser expenditures under various land tenure security states.

Land certification, previous certification experience, and farmers’ chemical fertiliser expenditure

Table 6 presents the estimated results of the new reform’s impact on farmer’s chemical fertiliser expenditures for different land certification experience groups. Preliminary results of the subsample estimation in columns (1) and (2) show that regardless of whether farmers had undergone land certification, the new reform had a negative and statistically significant impact on their chemical fertiliser expenditures. However, compared to farmers with previous land certification experience, those without such experience had slightly lower chemical fertiliser expenditures.

Table 6 Land certification and fertiliser expenditure: Heterogeneity test I.
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The results of the interaction item further prove that the above heterogeneous effects are statistically valid. The new reform has a greater impact on farmers with land certification experience than those without. Specifically, the estimates in column (3) indicate that, in the absence of previous land certification experience, the effect of the new reform is −0.101, statistically significant at the 1% level. Meanwhile, in the presence of previous land certification experience, the effect is −0.211 (−0.101–0.110), statistically significant at the 5% level. The possible explanation is that compared to farmers without land certification experience, those with such experience have a relatively clear and secure tenure and are more likely to trust and accept the new reform after 2013.

Land certification, previous adjustment experience, and farmers’ chemical fertiliser expenditure

Table 7 reports the new reform’s estimated effects on farmers’ chemical fertiliser expenditures for different land adjustment experience groups. Preliminary results of subsample estimation in columns (1) and (2) indicate that this impact differs among farmers with different land adjustment experiences. The new reform significantly reduces chemical fertiliser expenditure for farmers without land adjustment experience, while it does not affect farmers with previous land adjustment experience. The reason behind this may be that farmers with adjustment experience perceive it as a recurring event, regardless of whether the land is certified or not. Consequently, they may be less inclined to trust land certification due to the uncertainty associated with land tenure (Zheng and Qian, 2022).

Table 7 Land certification and fertiliser expenditure: Heterogeneity test II.
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Nevertheless, we do not observe a statistically significant change from the interaction item’s estimates in column (3), indicating that the abovementioned heterogeneous effects do not pass the formal test. This is likely because land adjustment in China’s rural society is decreasing under land laws. The penultimate row of Table 7 indicates that only 5.6% (1418/25,377) of farmers have undergone land adjustment prior to the new reform since 1997. In fact, as early as 1997, China’s Notice on Further Stabilising and Improving Rural Land Contracting Relations emphasised that the original contracted land should not be disrupted or re-contracted, nor the original land ownership’s boundaries be broken and redistributed evenly within the village. In 2002, the Land Contract Law of the People’s Republic of China stipulated that, except in a few special cases such as natural disasters that severely damage contracted land, village collectives should not adjust contracted land during the contract period.

Conclusions and discussion

Conclusions

Chemical fertilisers are the primary source of non-point source agricultural pollution, and promoting their reduction is a worldwide issue for sustainable agricultural development and food security. Through legal protection of land property rights, the new reform could theoretically help reduce farmers’ fertiliser expenditure and promote environment-friendly farming practices. This study used a three-period nationally representative panel dataset from the CFD for 2015–2019 and a propensity score matching and difference-in-difference approach to examine the role of land tenure reform on environment-friendly farming practices in rural China by evaluating the reduction effects of land certification on farmer’s chemical fertiliser expenditures.

We found that, first, land certification significantly reduces chemical fertiliser expenditures by about 15% on average, promoting environment-friendly farming practices. Meanwhile, we also observed a significant positive association between land certification and straw recycling and farm manure use. Second, land certification reduces farmers’ chemical fertiliser expenditure mainly by enhancing organic fertiliser investment, promoting land leasing, and inhibiting off-farm employment. Third, after considering the initial land tenure security in China, the impact of land certification on the reduction of chemical fertiliser expenditures is more significant for farmers with land certification experience. However, no significant difference exists in the effect of the new reform on farmers with and without land adjustment experience, as the probability of land adjustment under the current legal constraints is reducing constantly.

Policy implications

Given the significant impact of land certification on chemical fertiliser reduction, empirical findings from China are likely to be applicable to other developing countries.

First, developing countries can undertake large-scale land certification reforms like China, establishing land tenure protection for sustainable agricultural development. The main reason is that land tenure reform is closely linked to environment-friendly farming practices. Land certification will motivate farmers to reduce their reliance on chemical fertilisers and instead use recycled straw and farm manure and organic fertilisers as agricultural inputs. Second, it is imperative for developing countries to foster rural land rental markets and agricultural machinery service markets, facilitating the reduction of chemical fertilisers. With limited land resources, off-farm employment of rural labour is a prerequisite for the expansion of farm size, but also a trigger for increased use of chemical fertilisers. To this end, it is necessary to compensate for the shortage of agricultural labour and expand the size of farms by developing the market for machinery services and land rentals respectively, thereby reducing the use of chemical fertilisers. Third, developing countries need to take into account the differential impact of prior land tenure security and develop targeted incentives to promote environment-friendly farming practices. On the one hand, for farmers with more secure land rights, governments should continue to guarantee and enhance the security of their land rights. On the other hand, for farmers with less secure land rights, governments should build trust between the government and farmers through the construction of legal systems. Such measures may include prohibiting arbitrary land redistribution and issuing legally enforceable, multi-purpose land certificates to each farmer.

Research limitations and prospects

While this study investigates the link between land tenure reform and environment-friendly farming practices, data availability limits the scope and depth of the analysis, leaving several aspects to be further explored.

First, future research could use statistical data to investigate the macro-scale impact of land certification on chemical fertiliser use. This study utilises farm-level survey data to establish a positive relationship between land certification and chemical fertiliser expenditures at the micro-scale, but its validity at the macro-scale remains unconfirmed. Second, future research could identify more proxy variables for land tenure reform and examine other forms of land tenure reform. This study focuses on land certification as a proxy for land tenure reform due to the fundamental significance of property rights in property rights reform. Nevertheless, other reforms, including the implementation of the rural land contract law and three separation of land rights in rural China, also warrant scrutiny. Third, future research could establish an appropriate indicator system and further assess the impact of land tenure reform on environment-friendly farming practices in a comprehensive manner. This is of great academic importance because environment-friendly farming practices encompass various forms of implementation, such as tree planting, terraced field construction, and land composting, which also fall within this category.