Soil Use and Management

Abstract. Các cuộc khảo sát tài nguyên đất và đất đai khoa học chỉ có tác động hạn chế đến thực tiễn phát triển và mở rộng công nghệ ở các vùng nhiệt đới. Chúng được cho là không có nhiều liên quan đối với các nông dân tự cấp. Việc không thể đáp ứng các ưu tiên xã hội và văn hóa địa phương là một yếu tố. Các nhà khoa học đất đai cho đến gần đây đã ít chú ý đến sự hiểu biết của người khác về đất hoặc ‘nhân văn đất’. Việc kết hợp kiến thức về đất và tài nguyên đất từ dân tộc bản địa gần đây đã được đề xuất nhằm cải thiện tính liên quan của chúng. Tuy nhiên, một sai lầm phổ biến là áp đặt một mô hình khoa học phương Tây mà không phê phán, điều này có thể bóp méo sự hiểu biết. Kiến thức không thông suốt và không theo ngữ cảnh có thể dẫn đến các can thiệp tiêu cực. Bài báo này chỉ trích ý tưởng hạn hẹp về ‘kiến thức kỹ thuật bản địa’, trích dẫn bằng chứng từ Papua New Guinea, Bangladesh và Indonesia. Trong khi chúng tôi nhận thấy rằng nông dân nhất quán sử dụng một số thông tin tương tự như các nhà khoa học để đánh giá đất, các định nghĩa của họ về đất và các loại hình đất thường mâu thuẫn. Các nhà khoa học xác định các lớp dựa trên một loạt các đặc tính được đánh giá kỹ thuật, trong khi nông dân có thể không làm như vậy. Cách tiếp cận tổng thể hơn của họ cũng góp phần vào sự thiếu kết nối này, thường bao gồm cả các khía cạnh xã hội và văn hóa ngoại lai. Việc sử dụng rộng rãi hơn các khái niệm đất đai bản địa trong việc chuyển giao công nghệ nông nghiệp cũng có thể bị giới hạn bởi một số đặc điểm nội tại của chúng, có xu hướng đặc thù theo vị trí và tương đối theo văn hóa.

In order to tackle poverty and hunger in sub‐Saharan Africa (SSA) there is a strong case for a focus of effort on improving rainfed agricultural systems. The challenge is to deliver a transformation of agricultural productivity in such systems without adverse impacts on environmental goods and services. We examine the growing advocacy of ‘conservation agriculture’ (CA) as the desired approach and assess the evidence to support the assertion that it can deliver sustainable agricultural development in SSA. We examine in particular the evidence which derives from experience with ‘zero tillage sustainable agriculture’ in Brazil. We ask the question, is there a case for a paradigm shift in land husbandry? The case for a paradigm shift hangs on the premise that conventional practice promotes land degradation, while adoption of CA practice delivers a range of benefits through promoting soil ecosystem health. The guiding principle is to promote biological tillage through minimizing mechanical soil disturbance and maintaining permanent organic soil cover. We examine evidence of benefits in the context of the wider debate on low‐external‐input technology. We conclude that CA does not overcome constraints on low‐external‐input systems and will deliver the productivity gains that are required to achieve food security and poverty targets only if farmers have access to fertilizers and herbicides. We conclude also that widespread adoption of the new paradigm amongst millions of small farmers in order to achieve the ‘doubly green revolution’ in SSA is subject to the familiar constraints of knowledge transfer and success will depend upon creating innovation networks. Further, we conclude that amongst small‐scale farmers partial adoption will be the norm and it is not clear that this will deliver soil health benefits claimed for full adoption of the new paradigm.

Abstract. Composted domestic waste was applied either as a mulch or was incorporated into the topsoil. Mulching reduced the seasonal midday soil temperature ranges from between 14 °C and 27.5 °C to between 14 °C and 26 °C, averaging a 0.6 °C fall. However, at sub‐optimal temperatures for maize production under the temperate conditions of South East England, the difference may be critical. Compost mulch also improved soil‐water conservation in an average year, but not in a very dry year. Compost application increased soil‐available N, but increased K uptake was considered to be more important for crop yield than either N additions or the effect on retained soil water. Overall, compost applied as a surface mulch, or incorporated into medium‐textured soils in the south and east of England increased crop yield.

We studied the effects of applying different composts (urban organic waste, green waste, manure and sewage sludge), mineral fertilizer and compost plus mineral fertilizer on chemical, biological and soil microbiological parameters over a 12‐year period. The organic C and total N levels in soils were increased by all compost and compost + N treatments. Microbial biomass C was significantly (P ≤ 0.05) increased for some compost treatments. In addition, basal respiration and the metabolic quotient (qCO₂) were significantly higher in all soils that had received sewage sludge compost. The Shannon diversity index (H), based on community level physiological profiling, showed a higher consumption of carbon sources in soils treated with compost and compost + N compared with the control. The utilization of different guilds of carbon sources varied amongst the treatments (compost, compost + N or mineral fertilizer). Cluster analysis of polymerase chain reaction‐denaturing gradient gel electrophoresis patterns showed two major clusters, the first containing the mineral fertilization and compost treatments, and the second, the composts + N treatments. No differences in bacterial community structure could be determined between the different types of compost. However, the results suggest that long‐term compost treatments do have effects on the soil biota. The results indicate that the effects on the qCO₂ may be due to shifts in community composition. In this study, it was not possible to distinguish with certainty between the effects of different composts except for compost derived from sewage sludge.

For the past few years, the production of safe crops in Cd‐contaminated soil has attracted more and more attention, and the intercropping of wheat and herbaceous plants has gradually become an effective way. However, how the physicochemical and metabolic processes because of the intercropping change Cd availability are still unclear. In this study, we studied the influence of changes in soil physicochemical properties induced by intercropping of wheat with different herbs on soil Cd availability of Cd. Meanwhile, we innovatively studied the effect of intercropping on rhizosphere metabolites and evaluated the impact on Cd transfer. Results showed that the highest wheat biomass was presented in the intercropping system with the Cichorium intybus L. (W4) and Aus hypochondriacus L. (W5) increasing by 57.66% and 54.05% individually, compared with monocropping, while W1, W2, and W3 increasing slightly. Further, the Cd accumulation in wheat grains under W4 and W5 treatment decreased by 44.95% and 43.12%, respectively. Structural equation model confirmed that the increased pH, CEC contributed to the decreased Cd availability in soil, as well the changed metabolic profiles in wheat rhizosphere after intercropping. Specially, up‐regulation of fatty acid metabolism allowed wheat plants to maintain a normal intracellular environment under stress conditions. Similarly, up‐regulation of saccharide and amino acid metabolism induced the accumulation of sugars and proteins, which positively increased wheat biomass and Cd‐binding proteins, thus inhibiting the migration of soil Cd into wheat tissue. Collectively, this study provided reasonable insights towards understanding the metabolic mechanisms how intercropping altered Cd availability.

The England Catchment Sensitive Farming Delivery Initiative has recently identified 40 priority catchments where stakeholders require assistance with tackling harmful diffuse pollution, including that associated with phosphorus (P) and sediment. Newly appointed Catchment Sensitive Farming Officers require appropriate means of targeting P and sediment mitigation methods. In this context, the prototype PSYCHIC (Phosphorus and Sediment Yield CHaracterization In Catchments) model was used to characterize three pilot catchments in England, namely: the Derwent‐Cocker (626 km²), Teme (1623 km²) and Wensum (689 km²). Modelled annual total P export from the Derwent‐Cocker catchment is 1.2 kg ha⁻¹ year⁻¹, compared with 0.6 kg ha⁻¹ year⁻¹from the Teme catchment and 0.9 kg ha⁻¹ year⁻¹from the Wensum catchment. Corresponding sediment export is predicted at 271 kg ha⁻¹ year⁻¹, 124 kg ha⁻¹ year⁻¹and 70 kg ha⁻¹ year⁻¹, respectively. The findings highlight the importance of factors including P application rates, soil types and the increased connectivity provided by assisted drainage in determining pollution ‘hotspots’. Model output is being used to engage stakeholders and devise abatement strategies.

This paper analyses historic records of agricultural land use and management for England and Wales from 1931 and 1991 and uses export coefficient modelling to hindcast the impact of these practices on the rates of diffuse nitrogen (N) and phosphorus (P) export to water bodies for each of the major geoclimatic regions of England and Wales. Key trends indicate the importance of animal agriculture as a contributor to the total diffuse agricultural nutrient loading on waters, and the need to bring these sources under control if conditions suitable for sustaining ‘Good Ecological Status’ under the Water Framework Directive are to be generated. The analysis highlights the importance of measuring changes in nutrient loading in relation to the catchment‐specific baseline state for different water bodies. The approach is also used to forecast the likely impact of broad regional scale scenarios on nutrient export to waters and highlights the need to take sensitive land out of production, introduce ceilings on fertilizer use and stocking densities, and controls on agricultural practice in higher risk areas where intensive agriculture is combined with a low intrinsic nutrient retention capacity, although the uncertainties associated with the modelling applied at this scale should be taken into account in the interpretation of model output. The paper advocates the need for a two‐tiered approach to nutrient management, combining broad regional policies with targeted management in high risk areas at the catchment and farm scale.

We describe the development of a manual of methods for mitigating diffuse water pollution from agriculture and its important influence on policy and practice in England and Wales. The objective of the ‘User Manual’ was to provide policy makers and those implementing policies with information about the cost, effectiveness and applicability of potential methods in a form that would be readily understood by non‐specialists. The ‘User Manual’ was based on earlier reports synthesizing available research data and, where data were unavailable, used expert elicitation. The outcome generated 44 potential methods (under the broad categories of land use, soil management, livestock management, fertilizer management, manure management and farm infrastructure) and described the simultaneous impact of applying each method on losses of nitrate, phosphorus and faecal indicator organisms relative to baseline losses. Estimates of cost and effectiveness were presented at the whole‐farm level for seven model farm types. Methods differed widely in their cost‐effectiveness and applicability to the different model farms. Advantages and limitations of the approach are discussed and subsequent developments of the original ‘User Manual’ are described, together with the opinions of catchment officers who have used the ‘User Manual’ to implement mitigation methods on farms.

Abstract. A decision support system to predict the plant availability of nitrogen (N) following organic manure applications to land has been developed, drawing together the latest UK research information on factors affecting manure N availability and losses. The ADAS MANure Nitrogen Evaluation Routine (MANNER) accounts for manure N analysis, ammonia volatilization, nitrate leaching and mineralization of manure organic N. Only a few easily available inputs are required to predict the amount of N volatilized or leached, and the fertilizer N value for the next crop grown. Predictions from MANNER have been evaluated by comparison with independently collected data from a range of experimental studies where pig, cattle and poultry manures were applied to arable crops. Good agreement was found (r² 60–79%, P<0.001), confirming that MANNER can provide a reliable estimate of the fertilizer N value of farm manures spread to arable land under a range of conditions.

Conservation agriculture (CA) based onbest‐betcrop management practices may increase crop and water productivity, as well as conserve and sustain soil health and natural resources. In a 2‐year study, we assessed the effects of tillage and crop establishment (TCE) methods on productivity, profitability and soil physical properties in a rice–wheat (RW) system. The sixTCEtreatments were used to study the impact, which are puddled transplanted rice followed by conventionally tilled wheat (CTPR–CTW), direct‐seeded rice on the flat followed by zero‐till wheat (CTDSR–ZTW), zero‐till direct‐seeded rice with residue followed by zero‐till wheat with residue (ZTDSR+R–ZTW+R), transplanted rice after rotavator puddling followed by zero‐till wheat (RTTPR–ZTW), transplanted rice after rotavator puddling followed by rotary till wheat (RTTPR–RTW) and farmer practice rice–wheat (FP–RW). Result of the study revealed that mean rice yield was not significantly affected by differentTCEmethods. Wheat planted withZTDSR+R–ZTW+R gave 30% larger grain yield thanFP‐RW. Overall, among all theTCEtreatments, theRWsystem yields and net returns were maximum underZTDSR+R–ZTW+R. The fastest mean infiltration rate (0.10 cm hr^–1) was registered inZTDSR+R–ZTW+R plots, whereas the slowest was inFP‐RWplots (0.05 cm hr^–1). Bulk density at 15–20 cm soil depth was least inZTDSR+R–ZTW+R (1.70 Mg m^–3) and greatest inFP‐RW(1.73 Mg m^–3). Results from this study revealed that conventionally tilled (CT) and transplanting of rice could be successfully replaced by adoption of the profitable doubleZT–RWsystem.