Sewage Sludge: An Important Biological Resource for Sustainable Agriculture and Its Environmental Implications

Intensive farming generally needs large addition of organic matter to maintain fertility and enhance crop yields. Sewage sludge/biosolids are by-products of municipal and industrial wastewater treatment and a rich source of organic nutrients. Sewage sludge having high content of organic matter, macro- and micro-nutrients, can be used as fertilizer/soil conditioner for food, vegetable crop, horticultural plants and pasture, which in most cases can be beneficially recycled. In the past sewage sludge was regarded as a waste product due to expected high level of contaminants such as pathogens, pollutants and synthetic materials discharged in sewer from homes and industries, which were often incinerated, dumped in occasion or land fill. As a result of rapidly increasing population, urbanization and industrialization, wastewater production and sewage sludge generation have increased manifold. Due to high cost of mineral fertilizers and escalating trends in their prices, there is an increasing trend of using sewage sludge in agriculture, especially under intensive cropping in arid and semi arid regions of the country. Therefore, application of sewage sludge to agricultural soils may be sustainable and economical due to nutrient cycling and disposal of sewage sludge. However, there may be a risk in use of sewage sludge due to potentially harmful contents present in the sludge such as heavy metals and pathogens. This paper, therefore, presents a review on various aspects of sewage sludge used in agriculture.

Effect of Tillage and Nitrogen on Wheat Production, Economics, and Soil Fertility in Rice-Wheat Cropping System

Conservation tillage and nitrogen may improve soil fertility, yield and income on sustainable basis. The aim of this study was to evaluate the impact of three tillage systems viz. zero (ZT), reduced (RT), and conventional tillage (CT) and five N rates (0, 80, 120, 160, and 200 kg·N·ha-1) on yield and yield components, soil organic matter (SOM), total soil N (TSN), and income of wheat (Triticum aestivum L.) grown after rice (Oryza sativa L.). Nitrogen rates significantly affected yield and yield attributing characters with highest values recorded at200 kg·N·ha-1. Mean maximum grain yield (6390 -6845 kg·ha-1), net benefit (1359 - 1460 US$ ha-1), and benefit cost ratio (5.6 - 5.7) could be achieved at 160 to200 kg·N·ha-1. The tillage systems produced similar yield and yield components except spikes m-2. The SOM and TSN were highest in ZT compared to other tillage systems. Though tillage × N interactions were not significant for most of the parameters under study, the overall effect of ZT with200 kg·N·ha-1 appeared to be most favorable compared to RT and CT. Zero tillage resulted in highest number of spikes m-2 (304.4), SOM (9.6 g·kg-1) and TSN (0.5 g·kg-1) with200 kg·N·ha-1. The results suggest that ZT with200 kg·N·ha-1 was optimum and sustainable strategy to achieve higher yield and income and also to improve SOM and TSN on silty clay soil.

Ethnobotanical Study of Medicinal Plants of Semi-Tribal Area of Makerwal &Gulla Khel (Lying between Khyber Pakhtunkhwa and Punjab Provinces), Pakistan

This paper is based on the results of an ethnomedicinal research work conducted in the semi-tribal mountainous area lying between District Mianwali (PunjabProvince) and District Karak (KhyberPakhtunkhwaProvince),Pakistanduring June 2009-July 2011. During field survey, questionnaires were used to interview the local inhabitants of the area. The ethnomedicinal data consists of 131 plant species (2 Pteridophytes, 7 Monocots, 122 Dicots) belonging to 48 families (2 Pteridophytes, 4 Monocots, 42 Dicots). The most commonly represented families were Amaranthaceae (9 spp.), Mimosaceae (8 spp.), Asteraceae and Papilionaceae (7 spp.) each;Solanaceae, Euphorbiaceae and Scrophulariaceae (6 spp.) each, followed by Boraginaceae, Brassicaceae, Lamiaceae and Polygonaceae (5 spp.) each. Plant specimens were identified, preserved and vouchers were deposited in the Plant Taxonomy Lab. of Department of Biological Sciences,University of Sargodha,Pakistanfor future reference. The data collected through interviews with the local people indicates that these species are mostly used in respiratory tract infections (RTI), urinary tract infections (UTI), digestive disorders, sexual problems, skin diseases, liver ailments, wound healing, blood vomiting, malaria, piles, epilepsy, jaundice, gummosis, round worms, hepatitis etc. in the area. Due to lack of scientific approach regarding harvesting and utilization of this valuable medicinal flora, many plants are quickly going towards extinction;therefore, further work is needed to create awareness in the community conservation of the precious medicinal plants.

Ethnobotanical Studies on Dwarf Palm (<i>Nannorhops ritchieana</i>(Griff.) Aitchison) and Date Palm (<i>Phoenix dactylifera</i>L.) in Dera Ismail Khan, KPK, Pakistan

This paper is based on research work conducted during 2008-2010 in Dera Ismail Khan (D. I. Khan) District, Pakistan, to investigate Socio-Economic Impacts of Dwarf Palm (Nannorhops ritchieana) and Date Palm (Phoenix dactylifera) on the local inhabitants. A questionnaire for data collection of Dwarf Palm was designed and local people were interviewed. The main Dwarf Palm (Mazri) areas are lying between the Koh-i-Surkh and Marwat hill and yielding about 1000 tons of mazri leaves annually. Date Palm plantations are concentrated in Paniala, Paharpur, Chawdwan and Dhakki. The prominent varieties grown in the area are Dhakki, Shakri, Gulistan, Zaidi, Hillawi, Basra, Azadi and khudarawi. Dhakki Dates are well-known among all other varieties. Total area under dates cultivation in the district is 100,000 hectares, with total production of 11,000 tons dates. An average yield of Dhakki-Dates y-1 ranges from 6500 to 7000 tons i.e., 75% of the total production of dates in the area and dried dates production ranges from 800 - 1000 tons·year-1. A significant population is involved in processing of mazri and date palm leaves to prepare different products. Dates have a tremendous potential for economic uplift of the people. But growers face limitations and challenges regarding lack of information about customers and markets, harvesting, processing, and packaging techniques and infrastructure for producing good quality fresh dates. Fruit dropping in date palm particularly in Dhakki variety has become a serious concern. More than 70% date fruits drop before maturity. If production and processing constraints are properly handled, this may have significant socio-economic impact on local inhabitants.

Weeds of Wheat Crop and Their Control Strategies in Dera Ismail Khan District, Khyber Pakhtun Khwa, Pakistan

This study is based on research work conducted during 2008-2010 inDera Ismail Khan, KPK,Pakistan. The research area was extensively surveyed to investigate weed species. About 32 weed species, belonging to two monocot and thirteen dicot families, were collected from the study area. Plants were identified with the help of available literature and by comparing with the already identified plant specimens of the herbarium ofQuaid-i-AzamUniversity,Islamabad,Pakistan. Data inventory constitutes botanical name, vernacular name, English name, family, and flowering and fruiting period. Phalarus minor, Rumax dentatus, and Chenopodium album were the dominant weeds in the study area having comparatively higher relative weed density. Weeds having tough competition with wheat crop for light, moisture, and nutrients adversely affect wheat production. Hence, a constant effort is needed to keep the weed population under control. Many methods of weed control and eradication have been devised but chemical control is the most effective one. However, it may have some environmental consequences if not handled properly.