JWSS - Journal of Water and Soil Science

---

In order to find the critical period of weed control, the best time of weed control beginning (i.e. herbicide application time), and the length of weed control period (i.e. herbicide persistency) in corn, field experiments were conducted in Bajgah and Kooshkak in Fars Province in 1995 using a randomized complete block design with 14 treatments and four replications. Treatments consisted of different times of weed control beginnings (20, 30, 40, and 50 days after corn emergence), different duration of weed control periods (10, 20, and 30 days), a weedy check, and a weed-free check during the period of corn growth.

 In Kooshkak, a 10-day duration of weed control period had significantly lower corn yields than 20 and 30-day periods. In Bajgah, a 10-day weed control period had significantly lower corn yields than a 30-day period. Time of weed control beginning was not significant at both locations however, the interaction between beginning time and the duration period of weed control was significant. It appears in both locations that a minimum 20-day control period at the initial stages of corn and weed growth, and a minimum 30-day control period before corn pollination are necessary to prevent corn yield losses. In order to prevent corn leaf area decline at both locations, a 20-day weed control period until 40 days after crop emergence is necessary.

---

Solarization of field soil through mulching with transparent polyethylene sheets alone and in integration with farm yard manure (40 T/ha) and/or metalayl (25 kg/ha) during summer 1994-95 for five weeks in Isfahan resulted in an increase in temperature of 10 °C (± 1) and moisture preservation of up to 82%. Solarization effectively reduced foot-rot of cucumber (Phytophthora drechsleri) in the above treatments up to 88%, 96% and 95%, respectively.

Solarization, farm yard manure and their integration reduced the infection of Meloidogyne javanica up to 50%, 57% and 83% while plant parasitic nematodes were also reduced to 72%, 75% and 86%, respectively. The populations of free living nematodes increased only in farm yard manure and in integration with solarization by 30% and 53%, respectively.

Solarization effectively reduced the populations of almost all weeds by around 100%, except for Cyperus rotundus and Sonchus asper which were reduced by 59% and 44%, respectively.

---

Flora identification of each region plays an important role in the maintenance of natural resources of each country and it is a prerequisite to supplementary phylogenetics and genetic diversity studies. During February 1994 to August 1995, in a two-week interval, vineyards in two districts of Isfahan province, namely Zarinshahr and Tiran & Karvan were visited and weed samples were collected in flowering stages. All collected specimens were identified using specimens present in Herbarium of colleges of agriculture and natural resources of Isfahan University of Technology and other available references. The analysis revealed that in Tiran and Karvan, 84 species belonged to 71 genera and 26 families and in Zarinshahr 62 species belonged to 51 genera and 23 families. Species dominance in both districts belonged to Asteraceae and Gramineae families. Analysis of plant life forms using Raunkiaar method showed that Therophytes with 79.5% and Geophytes with 8.3% were the most frequent life forms in both Zarinshahr and Tiran & Karvan regions.

---

In the conventional methods of herbicide and fertilizer application, a substantial amount of toxic chemicals is sprayed or broadcast into the furrows, which is later washed away by irrigation water and may contaminate ground water, human and animal environment. If herbicide and fertilizer application could be limited to the most needed parts of the field rather than overall broadcasting, the mentioned problems could be alleviated and the application efficiency could also be increased by reducing the consumption rate. In an attempt to achieve this goal, a combination cultivator capable of simultaneously performing cultivation practices such as weed control (mechanical + chemical), fertilizer application and pest control was developed and evaluated. This machine was able to perform band spraying (fungicide, insecticide and herbicide) and mechanical cultivation (within-the-row weed killing, furrow reforming and hilling) simultaneously and properly. The combination cultivator was able to reduce herbicide consumption up to 66%.

---

The recent years' problems of herbicide use have led a growing number of researchers to seek alternative methods that are less reliant on herbicides. This research was conducted to determine the effect of long-term crop rotation, mineral fertilizer and herbicide on the weed infestation and grain yield of winter rye during 2004 and 2005 at the long-term experimental site of the University of Timiriazev, Moscow. Treatments were control (no weed control), herbicide, combined fertilizer (NPK) and NPK plus herbicide in field winter rye cultivated in continuous and crop rotation with other crops since 1912. Crop rotation significantly decreased weed density and dry mass. Long-term NPK application significantly decreased weed density, but had not any effect on weed dry mass. Crop rotation, NPK application and herbicide increased ground crop cover and decreased ground weed cover. In continuous crop, weed ground cover was 10 % in control plot and 3.33 % in plots where NPK was applied. Data showed that long-term crop rotation and NPK application can reduce weed infestation and increase grain yield of winter rye.