Phosphorus losses via surface runoff in rice-wheat cropping systems as impacted by rainfall regimes and fertilizer applications

Phosphorus（P） losses from agricultural soils contribute to eutrophication of surface waters. This field plot study investigated effects of rainfall regimes and P applications on P loss by surface runoff from rice（Oryza sativa L.） and wheat（Triticum aestivum L.） cropping systems in Lake Taihu region, China. The study was conducted on two types of paddy soils（Hydromorphic at Anzhen site, Wuxi City, and Degleyed at Xinzhuang site, Changshu City, Jiangsu Province） with different P status, and it covered 3 years with low, high and normal rainfall regimes. Four rates of mineral P fertilizer, i.e., no P（control）, 30 kg P ha^（–1） for rice and 20 kg P ha^（–1） for wheat（P_（30＋20））, 75 plus 40（P_（75＋40））, and 150 plus 80（P_（150＋80））, were applied as treatments. Runoff water from individual plots and runoff events was recorded and analyzed for total P and dissolved reactive P concentrations. Losses of total P and dissolved reactive P significantly increased with rainfall depth and P rates（P〈0.0001）. Annual total P losses ranged from 0.36–0.92 kg ha^–1 in control to 1.13–4.67 kg ha^–1 in P150＋80 at Anzhen, and correspondingly from 0.36–0.48 kg h^–1 to 1.26–1.88 kg ha^–1 at Xinzhuang, with 16–49% of total P as dissolved reactive P. In particular, large amounts of P were lost during heavy rainfall events that occurred shortly after P applications at Anzhen. On average of all P treatments, rice growing season constituted 37–86% of annual total P loss at Anzhen and 28–44% of that at Xinzhuang. In both crop seasons, P concentrations peaked in the first runoff events and decreased with time. During rice growing season, runoff P concentrations positively correlated（P〈0.0001） with P concentrations in field ponding water that was intentionally enclosed by construction of field bund. The relative high P loss during wheat growing season at Xinzhuang was due to high soil P status. In conclusion, P should be applied at rates balancing crop removal（20–30 kg P ha^–1 in this study） and at time excluding heavy rains. Moreover, irrigation and drainage water should be appropriately managed to reduce runoff P losses from rice-wheat cropping systems.

Soil and Crop Damages as a Result of Levee Breaches on Ohio and Mississippi Rivers

Whenever levees on the Ohio or Mississippi rivers are breached, there are soil damages in the flooded areas that impact agricultural management capacities and crop productivity. Floodwaters coat the entire flooded land surface with sediments which include a variety of pollutants, nutrients and contaminants. The nature of the sediments in floodwaters varies with the topographical and land use characteristics of the watershed. The soil types, hydro-geologic features, volume of flow, time of year, agricultural use of fertilizers, pesticides, and other chemicals as well as upstream point sources such as sewage treatment plants, storm sewer drainage and other urban land uses will affect the extent of the contamination and fine scale remediation needed. Preliminary characterization and measurement of soils and sediment deposit at three locations that experienced recent natural and man induced levee breaches are analyzed to identify patterns of soil and crop damage. These findings provide guidance to the restoration of craters, gullies, land scoured areas and contaminated sediment depositional sites with a goal to improve decision-making, risk analysis and remedial effectiveness. Recommendations include： （1） improve characterization and measurement of eroded soils and distribution of sediment contaminants after levee breaching; （2） assess contamination effects on soil productivity and long term agricultural production in order to understand the impacts of flooding on agricultural soils; （3） evaluate reconstruction investments needed to repair levees based on return of the land to productivity and increased landscape resilience by reducing vulnerability to future flooding and levee breaching stress.

Effect of potassium on soil conservation and productivity of maize/cowpea based crop rotations in the north-west Indian Himalayas

Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or long-term period. To test this hypothesis, a field experiment was performed in 2002-2003 and 2006-2007 to study the effect of K and several crop rotations on yield, water productivity, carbon sequestration, grain quality, soil K status and economic benefits derived in maize(Zea mays L)/cowpea(Vigna sinensis L.) based cropping system under minimum tillage(MT). All crops recorded higher grain yield with a higher dose of K(120 kg K2 O ha-1) than recommended K(40 kg K2 O ha-1). The five years' average yield data showed that higher K application(120 kg K2 O ha-1) produced 16.4%(P<0.05)more maize equivalent yield. Cowpea based rotation yielded 14.2%(P<0.05) higher production than maize based rotation. The maximum enhancement was found in cowpea-mustard rotation. Relationship between yield and sustainable indices revealed that only agronomic efficiency of fertilizer input was significantly correlated with yield. Similarly, higherdoses of K application not only increased the water use efficiency(WUE) of all crops, but also reduced runoff and soil loss by 16.5% and 15.8% under maize and 23.3% and 19.7% under cowpea cover, respectively. This study also revealed that on an average 16.5% of left over carbon input contributed to soil organic carbon(SOC). Here, cowpea based rotation with the higher K application increased carbon sequestration in soil. Potassium fertilization also significantly improved the nutritional value of harvested grain by increasing the protein content for maize(by 9.5%) and cowpea(by 10.6%). The oil content in mustard increased by 5.0% and 6.0% after maize and cowpea, respectively. Net return also increased with the application of the higher K than recommended K and the trend was similar to yield. Hence, the present study demonstrated the potential yield and profit gains along with resource conservation in the Indian Himalayas due to annual additions of higher amount of K than the recommended dose. The impact of high K application was maximum in the cowpea-mustard rotation.

Assessing Human-Wildlife Conflict in the Periphery of Loango National Park in Gabon

Human-Wildlife Conflict in Gabon is a reality occurring in almost all protected areas in the country. These conflicts create real threats both for the survival of wildlife species and of human beings. This study was carried out at the periphery of Loango National Park in Gabon. This area is particular of seeing elephants wandering around villages. Respondents for the study were drawn from a wide range of stakeholders (State administrators, farmers and NGOs). Data was collected through administration of structured questionnaires and interview guide on the;socio-economic activities. Crops produced/destroyed. Animals are involved and economic loss is incurred due to conflicts. Data was analysed using SPSS version 16 and Kobo tool box. For qualitative data chi-square, descriptive statistic and linear regression model were also used. The results of the study showed that the elephants account for (60.1%) of crop destroyed followed by Ungulates (30.4%) and lastly by rodents (0.9%). The economic damage caused by the wildlife to crops valued at 72,084 USD in the zone in 2022. An urgent solution to this conflict is needed because the consequences are visible as well as the illegal repression by communities that have led to poisoning and killing of wildlife in the study area.

Disease detection,severity prediction,and crop loss estimation in MaizeCrop using deep learning

The increasing gap between the demand and productivity of maize crop is a point of concern for the food industry,and farmers.Its'susceptibility to diseases such as Turcicum Leaf Blight,and Rust is a major cause for reducing its production.Manual detection,and classification of these diseases,calculation of disease severity,and crop loss estimation is a time-consuming task.Also,it requires expertise in disease detection.Thus,there is a need to find an alternative for automatic disease detection,severity prediction,and crop loss estimation.The promising results of machine learning,and deep learning algorithms in pattern recognition,object detection,and data analysis motivate researchers to employ these techniques for disease detection,classification,and crop loss estimation in maize crop.The research works available in literature,have proven their potential in automatic disease detection using machine learning,and deep learning models.But,there is a lack none of these works a reliable and real-life labelled dataset for training these models.Also,none of the existing works focus on severity prediction,and crop loss estimation.The authors in this manuscript collect the real-life dataset labelled by plant pathologists.They propose a deep learning-based framework for pre-processing of dataset,automatic disease detection,severity prediction,and crop loss estimation.It uses the K-Means clustering algorithm for extracting the region of interest.Next,they employ the customized deep learning model‘MaizeNet’for disease detection,severity prediction,and crop loss estimation.The model reports the highest accuracy of 98.50%.Also,the authors perform the feature visualization using the Grad-CAM.Now,the proposed model is integrated with a web application to provide a userfriendly interface.The efficacy of the model in extracting the relevant features,a smaller number of parameters,low training time,high accuracy favors its importance as an assisting tool for plant pathology experts.The copyright for the associated web application‘Maize-Disease-Detector’is filed with diary number:17006/2021-CO/SW.

Assessment of soil loss and nutrient depletion due to cassava harvesting:A case study from low input traditional agriculture

Cassava is a major food crop for farmers and especially small holder farmers and cultivated under low input other than the irrigation.It is cultivated as mono crop or intercrop at early stage and cultivating throughout the year.It is harvested carefully because of cyanogenic glucosides and consumed with in day.Easy and un-damageable uprooting of the tuber mainly depends on soil moisture,texture and agronomic practices.The study was focused with the objectives of the assessment of soil loss due to the harvesting of cassava roots tubers under low input agriculture,and to estimate the amount of plant nutrients loss due to crop harvest for cassava.Also the observation was made the correlation between the soil loss and physical characters of the tuber,soil texture and agronomic practices.Average plant specific soil loss due to crop harvesting was 80.7 g root−1 and crop specific soil loss due to crop harvesting was 7.64 kg ha−1 harvest−1 loss in Valliagmam area in Jaffna,Sri Lanka.Soil moisture content at harvesting time was a significant factor that explained the variations in the soil lost at cassava harvesting.Soil moisture has linear positive relationship with average plant specific soil loss due to crop harvesting.Soil nutrient loss during cassava harvesting by removal of adhering soil with root tuber was 1.15 kg of N,1.99 kg of P and 2.91 kg of K ha−1 harvest−1.Application of fertilizer is important since considerable amount nutrient loss was observed due to soil loss due to crop harvest.