A Micro Level Investigation of Costs & Returns of Different Agro-ecosystems in Kashmir Region of Jammu and Kashmir: India

The basic objectives of the study were to enquire in to the involvement of various types of costs, the returns per rupee invested and the benefit thereof in different agro-ecosystems in the state of Jammu and Kashmir in general and valley of Kashmir in particular, especially the sampled districts. This study was based upon primary and secondary data. A multi-stage random sampling was utilised for collection of date from 432 respondents of four different agro-ecological zones. For major crops, the cost of cultivation were estimated by concept utilised by Commission on Agricultural Costs and Prices (CACP), Government of India. The results revealed that fruit crop agro-ecosystem is highly remunerative than field crop and crop agro-ecosystems, though the fruit crop involve huge of investment in terms of different costs. The livestock based agro-ecosystem is also dominant in some parts of the Kashmir region with declining trend. The results revealed that the gross returns of paddy and apple, livestock and cash crop were Rs. 23250, Rs. 321000, Rs. 108920 and 106915 respectively. This study had its applicability in the daily routine life of any household dwelling in the sampled agro-ecosystems. The study could be of utmost importance in selecting the crop in which the region/agro-ecosystem had specialisation or absolute advantage.

Water use in four model tropical plant associations established in the lowlands of Costa Rica

We examined soil water use patterns of four model plant associations established in the North Caribbean lowlands of Costa Rica by comparing the stable hydrogen isotope composition, δD, in xylem sap and in soil water at different depths, under rainy and dry conditions. Four 5-year-old model plant associations composed of 2 tree species (Hyeronima alchorneoides and Cedrela odorata) having different architecture and phenology were studied. Average tree height was 8.9 and 7.6 m, respectively. Each tree species was grown in monoculture and in polyculture with 2 perennial monocotyledons (Euterpe oleracea and Heliconia imbricata). Maximum rooting depth at the time of δD determination was ~ 2 m for almost all species. Most roots of all species were concentrated in the upper soil layers. Stomatal conductance to water vapor (gS) was higher in the deciduous C. odorata than in the evergreen H. alchorneoides; within each species, gS did not differ when the trees were grown in mono or in polyculture. During the rainy season, gradients in soil water δD were not observed. Average rainy season xylem sap δD did not differ among members of the plant combinations tested (-30 ‰), and was more similar to δD values of shallow soil water. Under dry conditions, volumetric soil water content declined from 50 to ~ 35%, and modest gradients in soil water δD were observed. xylem sap δD obtained during dry conditions was significantly lower than rainy season values. xylem sap δD of plants growing in the four associations varied between -9 and -22‰, indicating that shallow water was predominantly absorbed during the dry period too. Differences in xylem sap δD of trees and monocots were also detected, but no significant patterns emerged. The results suggest that: a) the plant associations examined extracted water predominantly from shallow soil layers (<1 m), b) the natural isotopic variation in soil and plant water at the study site was low, and c) the plant mixes obtain water from more than a single soil layer simultaneously. Temporal factors were important in determining the competition and complementary relations observed among the trees and the perennial monocots. Under the prevailing environmental conditions, water use in these plant associations was determined largely by species-specific attributes such as biomass allocation to fine roots, phenology, and canopy architecture, and to a lesser extent by water limitations. Rev. Biol. Trop. 56 (4): 1947-1957. Epub 2008 December 12.

Examinamos los patrones de uso de agua del suelo de cuatro asociaciones vegetales establecidas en el Caribe norte de Costa Rica, comparando la composición isotópica del hidrógeno, δD, en la savia del xilema y en el agua del suelo en condiciones lluviosas y secas. Estudiamos cuatro asociaciones de cinco años de edad compuestas por dos árboles (Hyeronima alchorneoides y Cedrela odorata) con diferente arquitectura y fenología, cultivados en mono y policultivo con dos monocotiledóneas perennes (Euterpe oleracea y Heliconia imbricata). Las excavaciones mostraron que la profundidad máxima de las raíces fue de 2 m para casi todas las especies, y que la mayor densidad de raíces se encontraba en la superficie del suelo. La conductividad estomática (gS) fue mayor en el árbol caducifolio (C. odorata) que en el perennifolio (H. alchorneoides); dentro de cada especie, gS no difirió cuando los árboles fueron cultivados en mono o en policultivo. Los resultados sugieren que: a) las asociaciones examinadas extrajeron agua predominantemente de las capas superficiales del suelo (<1 m), b) la variación natural en el acceso al agua del suelo por parte de las especies, y en las propiedades del suelo, fue baja, y c) las combinaciones de plantas obtuvieron agua de varias capas del perfil del suelo simultáneamente. Los factores relacionados con el tiempo fueron importantes en la determinación de las relaciones de competencia y complementariedad observadas entre los árboles y las monocotiledóneas perennes. En las condiciones ambientales prevalecientes, el uso del agua por parte de estas asociaciones de plantas fue determinado más por atributos, como la asignación de biomasa a las raíces finas, la fenología, y las propiedades del dosel, que por limitaciones en la disponibilidad de agua.

Natural regulation of white grub (Holotrichia sp: Scarabidae) by birds in agroecosystem.

The white grub (Holotrichia sp: Scarabidae) is an important subterranean pest damaging root systems of several crops. Experiments conducted during I985 and I986 showed that at least I4 species of birds picked up the grubs exposed during ploughing operation. The important bird predators were mynas Acridotheres tristis (Linnaeus) and Acridotheres ginginianus (Latham), crows Corvus splendens (Vieillot), Corvus macrorhynchos (Sykes), drongo Dicrurus adsimilis (Hodgson) and cattle egret Bubulcus ibis. The birds were found to reduce 45 to 65% grub population during 3 subsequent ploughings. The plant stand of second crop raised in bird exposed field was higher in experimental plot compared to the control. The number of birds attracted to the plough was not consistent with the density of grubs exposed but oh many extraneous factors. Factors affecting the extent of bird predation were presence of insectivorous birds in the surroundings, proximity to their breeding sites and timing of ploughing. White grub control by birds is economically cheaper and environmentally safe compared to the chemical control.