Effects of ridge-furrow rainwater harvesting with maize straw biochar on fodder yield and water use efficiency of alfalfa in semiarid regions of China

Journal of Soils and Sediments - On a global scale, water resources are under intense stress due to climate change. It is, therefore, crucial to understand how in situ water harvesting techniques...     

Soil Nutrients Status after Fifty Years of Tillage and Nitrogen Fertilization

Long-term studies are valuable in assessing the impact of crop management practices on soil sustainability and function. This study used two calculation scenarios, fixed depth and Equivalent Soil Mass (ESM) to assess (i) soil nutrient status and (ii) soil organic carbon (SOC) after 50 years of nitrogen (N) fertilizer application rates (0, 22, 45, and 67 kg N ha^?1) and tillage [clean tillage (CT), reduced tillage (RT), and no-tillage (NT)] in a dryland winter wheat-sorghum-fallow cropping system. The soil organic matter (SOM) content increased by 33% with NT and RT compared with CT. The SOC at 0–30 cm was 39% greater than 30–60 cm depth with both fixed depth and ESM calculations. Soil nutrient specifically soil calcium (Ca), magnesium (Mg), and phosphorus (P) associated with N rates were no different than the control. Crop nutrient removal may eventually reduce soil nutrient contents with only N application. Nutrient addition specifically P should be considered in the future.     

Impact of maize straw biochar and tied-ridge-furrow rainwater harvesting on soil erosion and soil quality in a semiarid region

In dryland areas, integrating biochar soil amendment with in situ rainwater harvesting systems may decrease soil erosion, improve soil quality, and increase crop productivity and yield. This study was conducted to investigate the effect of maize straw biochar amendment and ridge-furrow rainwater harvesting systems on run-off, sediment yield and the physico-chemical properties of a Calcic Cambisol soil in semiarid areas. The experiment was conducted on alfalfa (Medicago sativa) production land at the Anjiagou Catchment experimental station in Gansu province, China. The experimental layout was a split-plot design with three replications. Biochar was applied at a rate of 0 and 30 t ha⁻¹, respectively. The tillage treatments were flat planting, open-ridging, and tied-ridging (TR). Overall, the integration of maize straw biochar with TR decreased soil bulk density at 0–40 cm depth. Biochar application reduced run-off by 37.8% and soil loss by 55.5% during alfalfa-growing seasons compared to the control. In general, biochar addition increased soil total potassium, but the same effect was not observed for soil pH, total nitrogen, total phosphorus, and available phosphorus. These findings demonstrate the potential of integrating maize straw biochar and tillage systems to reduce soil erosion and improve soil quality for rainfed crop production in semiarid areas. Further studies on the effect of biochar-tillage system interaction are warranted to improve soil conditions for plant growth and increase crop yield in dryland areas.     

Predicting soil workability and fragmentation in tillage: a review

Soil workability and friability are required parameters to consider when creating suitable seedbeds for crop establishment and growth. Knowledge of soil workability is important for scheduling tillage operations and for reducing the risk of tillage‐induced structural degradation of soils. A reliable evaluation of soil workability implies a distinctive definition of the critical water content (wet and dry limits) for tillage. In this review, we provide a comprehensive assessment of the methods for determining soil workability, and the effects of soil properties and tillage systems on soil workability and fragmentation. The strengths and limitations of the different methods for evaluating the water content for soil workability, such as the plastic limit, soil water retention curve (SWRC), standard Proctor compaction test, field assessment, moisture‐pressure‐volume diagram, air permeability and drop‐shatter tests are discussed. Our review reveals that there is limited information on the dry limit and the range of water content for soil workability for different textured soils. We identify the need for further research to evaluate soil workability on undisturbed soils using a combination of SWRC and the drop‐shatter tests or tensile strength; (i) to quantify the effects of soil texture, organic matter and compaction on soil workability; and (ii) to compare soil water content for workability in the field with theoretical soil workability, thereby improving the prediction of soil workability as part of a decision support system for tillage operations.     

Impact of tillage intensity on clay loam soil structure

Soil structure and structural stability are key parameters in sustainable soil management and optimum cropping practices. This study aimed to improve the knowledge of potential precision tillage practices by characterizing the effect of varied tillage intensities on structural properties of a clay loam soil. An experiment with seedbed preparation was conducted using a power take‐off‐driven rotovator equipped to measure torque and angular velocity and with operational speed (OS) and rotational speed (RS) as main factors. Effects of soil coverage prior to tillage and wheeling directly after tillage were measured at one combination of OS and RS. The soil was sampled at 0–80 mm depth. Under slow OS (2.9 km hr^?1) compared with fast OS (6.3 km hr^?1), specific energy input was greater (116 and 52 J kg^?1 on average, respectively), and it increased with RS. Wheeling resulted in larger aggregate diameter right after tillage (at T1; 56 mm as geometric mean compared with 9 mm), with 42 times smaller geometric mean of air permeability 45 days after tillage (at T2) and with greater soil dispersibility at T2. Highly significant correlations were observed between soil dispersibility and energy input, specific surface area of aggregates, fractions of small (<4 mm) and medium (8–16 mm) aggregates, and geometric mean diameter. Slow OS combined with fast RS showed significantly greater air permeability than all other treatments. The results suggest that there is a potential for controlling soil structure in seedbed preparation by minimizing compaction from traffic and adapting site‐specific control of rotovation intensity.     

USING TISSUE ANALYSIS AS A TOOL TO PREDICT BAHIAGRASS PHOSPHORUS FERTILIZATION REQUIREMENT

Tissue analysis in combination with soil testing has been recently incorporated in the fertilization recommendations for bahiagrass in Florida; however, limited research is available to validate the proposed critical tissue phosphorus (P) level. A greenhouse experiment was conducted to identify the critical minimum tissue P concentration below which bahiagrass dry matter (DM) yield is impacted. Treatments consisted of three nitrogen (N) rates (0, 50, and 100 kg N ha^?1), four P rates (0, 20, 40, 60 kg P₂O₅ ha^?1) and two clipping intervals (28 and 56 d). Bahiagrass yields and tissue P increased in response to P application. Phosphorus uptake showed a quadratic response to P rates when N was applied. Phosphorus recovery increased linearly as P rate increased. Root mass responded to P, even at the smallest (20 kg ha^?1) rate. Data indicated that tissue P concentration of 1.3 (±0.2) g kg^?1 can be used as an indicator of bahiagrass P deficiency.     

Long-term residual effects of feedlot manure application on crop yield and soil surface chemistry

Crop response to manure application may extend beyond the year of application due to residual nutrient availability. A field experiment was conducted to evaluate feedlot manure application (at 0 22.5, 45, 90 and 180 Mg ha^?1) and subsequent residual effects (24-yr) on wheat and sorghum grain yields. Sorghum grain yields increased significantly with manure and nitrogen (N) fertilizer application. However, winter wheat grain yield showed no consistent response to manure and fertilizer application in the 9-yr when manure was applied. Averaged across the subsequent 24 years, residual feedlot manure and annual N fertilizer application significantly increased sorghum and winter wheat grain production. Application of cattle manure did increase soil organic matter content, pH and plant available soil nutrients. Our finding showed that growers could take advantage of the long-term benefits of nutrients supplied from manure application to bolster crop production, improve soil quality and reduce fertilizer input cost.     

Evaluating grain sorghum hybrids for tolerance to iron chlorosis

Grain sorghum production in calcareous soils is frequently affected by iron (Fe) chlorosis. Greenhouse experiments were conducted to screen sorghum hybrids for their tolerance to iron deficiency chlorosis (IDC) and evaluate the effectiveness of Fe chelate application in alleviating IDC. Treatments in Exp. 1 were a factorial combination of 14 sorghum hybrids and three Fe chelate application rates (0, 3.4 and 6.8?kg product ha^?1) applied in-furrow with the seed at the time of planting. Exp. 2 evaluated two sorghum hybrids (85Y40 and NK5418) and three Fe chelate rates (0 and 3.4?kg product ha^?1) at planting, and a split treatment of 3.4?kg ha^?1. Results showed iron chelate application suppressed IDC and increased leaf chlorophyll content and grain yield in susceptible hybrids. Split application of Fe chelate suppressed IDC and increased grain yield. Our results indicate sorghum hybrids G8G08, 86G32 and 87P06 showed promise for tolerance to IDC.