Agricultural Systems ( IF 6.1 ) Pub Date : 2021-08-05 , DOI: 10.1016/j.agsy.2021.103242 Katrin Rudolf 1 , Nina Hennings 2 , Michaela A. Dippold 2 , Edi Edison 3 , Meike Wollni 1, 4
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CONTEXT
The area under oil palm cultivation has expanded importantly in South-East Asia. The resulting land-use transformations are associated with environmental degradation such as substantial carbon dioxide emissions. Soil conservation practices can contribute to more sustainable oil palm systems by increasing soil organic carbon (SOC) contents and yields. One soil conservation practice in oil palm plantations is the mulching with empty fruit bunches (EFB).
OBJECTIVE
We estimated the relationship between EFB mulching and, respectively, yields, SOC and total nitrogen contents, the carbon‑nitrogen ratio and the average bulk density in smallholder oil palm plantations. We further analyzed the determinants of smallholders' EFB application taking into account regional market, farm, and plot level aspects, as well as farmers' perceptions.
METHODS
We estimated the relationship between mulching and yields with panel data, and between mulching and soil properties with cross-sectional data. We accounted for the possible selection bias of the decision to apply EFB mulching with instrumental variable estimations. Descriptive analysis was used to analyze the determinants of smallholder EFB use.
RESULTS AND CONCLUSIONS
Our results indicated that in particular the regional supply in EFB and farmers' wealth levels were correlated with smallholder EFB mulching. EFB mulching was associated with 39% higher yields and 19% higher SOC contents. We attribute the higher yields to potentially improved soil chemical functions linked to higher SOC contents, such cation exchange capacity effects, and to an increased K and potentially Mg availability. Since EFB is not available in sufficient quantity to be applied to all plantations, policy makers could identify user groups with the greatest potentials for environmental and income improvements. Site-specific life cycle assessments and yield effects can help to inform such identification.
SIGNIFICANCE
Despite their growing importance in the oil palm sector, evidence on the effect of EFB mulching was missing for smallholder farmers. Because of associated higher SOC contents and yields, our findings indicate that the promotion of EFB mulching as best management practice could potentially contribute to more sustainable oil palm systems. Strengthening inclusive value chains for smallholders, information provision and investments in road infrastructure represent potential policy instruments to increase smallholder EFB application. The identification and promotion of best management practices are important with view to the still ongoing oil palm expansion in South-East Asia, and progressively in other parts of the world.
中文翻译：
改善油棕小农场的经济和环境成果：覆盖、土壤特性和产量之间的关系
语境
油棕种植面积在东南亚显着扩大。由此产生的土地利用转变与环境退化有关，例如大量的二氧化碳排放。土壤保护实践可以通过增加土壤有机碳 (SOC) 含量和产量来促进更可持续的油棕系统。油棕种植园的一种土壤保持实践是用空果串 (EFB) 进行覆盖。
客观的
我们分别估算了 EFB 覆盖与小规模油棕种植园的产量、SOC 和总氮含量、碳氮比和平均容重之间的关系。我们进一步分析了小农 EFB 应用的决定因素，同时考虑了区域市场、农场和地块层面以及农民的看法。
方法
我们用面板数据估计了覆盖和产量之间的关系，用横截面数据估计了覆盖和土壤特性之间的关系。我们考虑了使用工具变量估计应用 EFB 覆盖的决定可能存在的选择偏差。描述性分析用于分析小农 EFB 使用的决定因素。
结果和结论
我们的结果表明，特别是 EFB 的区域供应和农民的财富水平与小农 EFB 覆盖相关。EFB 覆盖与 39% 的更高产量和 19% 更高的 SOC 含量相关。我们将较高的产量归因于与较高 SOC 含量相关的潜在改善的土壤化学功能，例如阳离子交换容量效应，以及增加的 K 和潜在的 Mg 可用性。由于 EFB 的数量不足以应用于所有种植园，政策制定者可以确定在环境和收入改善方面具有最大潜力的用户群体。特定地点的生命周期评估和产量效应有助于为此类识别提供信息。
意义
尽管它们在油棕部门中的重要性日益增加，但缺乏关于小农户 EFB 覆盖效果的证据。由于相关的 SOC 含量和产量较高，我们的研究结果表明，将 EFB 覆盖作为最佳管理实践的推广可能有助于更可持续的油棕系统。加强小农的包容性价值链、信息提供和道路基础设施投资是增加小农 EFB 应用的潜在政策工具。鉴于东南亚仍在进行的油棕扩张以及世界其他地区的逐步扩张，确定和推广最佳管理实践非常重要。
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